From Newsgroup: comp.mobile.android

Tutorial:
Garmin-style GPS-only Android location-privacy Maps/Route/Traffic

Nuclear shortcut (this works, but it's generally considered impractical).
A. Airplane mode = ON
B. GPS (Location radio) = ON
C. Maps/routing/traffic done offline
Everything else stays OFF by default in airplane mode.
Result: GPS-only fixes, no scanning, no uploads, no auto-connects.

Non-nuclear switches and their positions (which allow for nuanced options):
1. Location radio = ON
2. Cellular voice radio = OFF
3. Cellular data radio = OFF
4. Bluetooth radio = OFF
5. Wi-Fi radio = OFF
6. Wi-Fi scanning = OFF
7. Bluetooth scanning = OFF
8. Google Location Accuracy = OFF
9. Precise Location = ON
10. In apps, choose GPS only
11. Wi-Fi auto-reconnect = OFF
12. Airplane mode = ON when you want maximum privacy
13. Wi-Fi calling = OFF
14. NFC = OFF
15. Sensors = restrict app access

Overview:
This checklist shows how we can configure Android so that apps use
only the GPS chip for location, without leaking extra data to
carriers, Google or to nearby Wi-Fi/Bluetooth beacons. By turning
radios, scanning, and auto-reconnect OFF (except GPS), we can
approximate the "GPS-only" privacy we had with standalone Garmin
units of yesteryear, while still allowing apps to read satellite fixes.

Details (which allow for nuanced tradeoffs):
1. Location radio = ON
(needed for GPS to work)

2. Cellular voice radio = OFF (more about turning it on will come later)
(eliminates tower-based coarse location)

3. Cellular data radio = OFF (more about turning it on will come later)
(blocks apps and Google services from sending precise location
over mobile data, and prevents network-assisted GPS lookups)

This stops your phone from sending any data over the mobile
data channel. That includes uploads of Wi-Fi SSIDs/BSSIDs and
Bluetooth beacon information.

However, if Wi-Fi is ON and connected, or if Wi-Fi/BT scanning
is enabled, the operating system can still collect those signals
and may upload them through Wi-Fi instead of cellular.

To fully prevent uploads of neighbor Wi-Fi and Bluetooth beacons,
you must also turn OFF Google Location Accuracy, Wi-Fi scanning,
and Bluetooth scanning.

4. Bluetooth radio = OFF (more about turning it on will come later)
(optional, improves privacy if you do not need headsets or wearables)

Even if scanning is OFF, with the radio ON the phone can still
advertise its own presence, exchange metadata with paired devices,
and reveal its Bluetooth MAC address. With the radio OFF, none
of that is possible.

5. Wi-Fi radio = OFF (more about turning it on will come later)
(optional, improves privacy if you do not need Wi-Fi data)

Even if scanning is OFF, with the radio ON the phone can still
broadcast probe requests for known networks and reveal its Wi-Fi
MAC address. With the radio OFF, none of that is possible.

By default, current Android releases randomize the MAC per AP.
If desired, Developer Options allow randomizing per connection.

6. Wi-Fi scanning = OFF (more about turning it on will come later)
(no Wi-Fi beacon frames logged)

7. Bluetooth scanning = OFF (more about turning it on will come later)
(no BT beacons logged)

When Wi-Fi or Bluetooth scanning is ON:

The phone continuously listens for nearby Wi-Fi access points
and Bluetooth beacons. It records identifiers such as SSID,
BSSID (MAC address), signal strength, and sometimes timestamps.

These scan results are cached locally by the operating system.
They are not immediately uploaded every time they are seen.

When network connectivity is available (cellular data or Wi-Fi),
the cached scan results can be uploaded later to services such
as Google Location Accuracy. This is how the global database
of Wi-Fi and BT beacons is maintained.

When scanning is OFF:

The phone does not collect those identifiers in the background,
so there is nothing to cache or upload later.

8. Google Location Accuracy = OFF (more about turning it on later)
(disables the fused provider and prevents uploads to Google)

9. Precise Location = ON (more about turning it off will come later)
(so apps can still use the GPS chip directly)

10. Some apps allow you to choose the location provider, such as SatStat
<com.vonglasow.michael.satstat>, so, for those, choose GPS only
(not fused, network, or passive)

11. Turn each AP Wi-Fi auto-reconnect = OFF for all hidden or common SSIDs.
(prevents the phone from automatically probing for saved networks)
(prevents the phone from connecting to rogue evil-twin SSIDs)

Anyone not hiding their home AP SSID broadcast and/or note adding
the _nomap prefix is explicitly asking to be in Google's database.

With auto-reconnect ON, the phone broadcasts probe requests
for SSIDs it has saved, which can reveal your network history
to anyone sniffing nearby. With auto-reconnect OFF, you must
manually choose a network each time, and your phone does not
advertise that history list in the background.

12. Airplane mode = OFF (see nuclear mode if turning it on)
(GPS still works receive only when airplane mode is on)

13. Wi-Fi calling = OFF
(prevents call/SMS metadata from leaking location through Wi-Fi)

14. NFC = OFF
(prevents the phone from responding to nearby NFC readers)

15. Sensors = restrict app access
(accelerometer, gyroscope, barometer, etc. cannot be globally disabled
without root; control access through app permissions for map apps)

This is my first-pass best-guess comprehensive method to obtain as close to Garmin-style location privacy as we can get on a non-rooted Android phone.

Obviously I'm aware that the voice radio is needed for calls & that the cellular data radio is desirable for online maps/traffic, and that the bluetooth radio might be used for speakers, etc., so explicit tradeoff
choices that most of us must make as a result will be discussed later.
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