As far as I know, the only way to install independent WearOS apps is to enable developer options on the watch and turn on ADB debugging. For installation without the use of a PC, see “Without PC” below.
For instruction on how to install an APK on WearOS see:
https://www.droidwin.com/sideload-apk-install-apps-via-adb-commands-in-galaxy-watch-5-pro
https://www.guidingtech.com/how-to-install-apks-on-wear-os-smartwatches
https://www.reddit.com/r/WearOS/comments/p1l9of/how_to_install_apps_on_wear_os_all_methods/
First you need to get adb, see https://www.xda-developers.com/install-adb-windows-macos-linux/
Download adb:
adb is included in the SDK platform tools of Android and also in most Linux distributions. You also need to enable developer options on your watch (https://developer.android.com/training/wearables/get-started/debugging):
How exactly you have to do it, differs per watch. On Watch4 you have to press on "About Watch" in Settings. Press on "Software Info" and then touch 7 times "Software version". You can turn it off again by doing the same, so if you do it too long it is turned off again.
Now an item called "Developer options" is added to Settings. Here "ADB Debugging" and "Debug over Wi-Fi" should be turned on.
Ensure that WIFI is stably turned on on your watch. If it is not, go in Juggluco on your watch to Left menu->Mirror and turn on WIFI (remember to turn it off later).
Get your watch IP. In Watch4 you can find it be going to settings->Connections->Wifi and pressing on your connection. At the bottom you find the IP address of the watch.
On your computer press:
adb connect IP-of-watch
IP-of-watch stands for the IP address of your watch. As described in the WearOS4.0, this is now different for Samsung Galaxy WearOS watches.
On your watch you are asked: allow debugging?
Press Yes or Always allow from this computer.
Hereafter
adb devices
should show something like:
192.168.1.73:5555 device
Now you can install Juggluco with the following command:
adb install -r apkfile
Here "apkfile" stands for the apk file you previously downloaded from https://www.juggluco.nl/Juggluco/download.html. If that file was Juggluco4.6.1-wear-arm32.apk, it becomes:
adb install -r Juggluco4.6.1-wear-arm32.apk
The -r option is only needed for an update (when Juggluco was already installed on the watch).
On Samsung Galaxy Watch 4, the update to WearOS4.0/Android 13 changed the use of adb. See WearOS4.0 for more information. The same will also apply to Watch 5 and 6.
To use adb in the above manner under bash or powershell, adb's location should be in the PATH environmental variable. You can set that in the following way:
Linux:
If adb is located /home/jka/Android/Sdk/platform-tools, you type:
export PATH=/home/jka/Android/Sdk/platform-tools:$PATH
Windows Powershell:
If adb is located in C:\Android\platform-tools, do
$Env:PATH+=";C:\Android\platform-tools"
Windows cmd.com:
set PATH=%PATH%;C:\Android\platform-tools
You can also run the commands from the place were adb is located and using ./adb instead of adb under Linux and .\adb instead of adb under Windows.
When you don’t have access to a computer, it is still possible to install Juggluco for WearOS:
Install TERMUX on a phone or tablet. Install android-tools:
apt install android-tools
and use adb from your phone or tablet to the watch.
Install GeminiMan WearOS Manager from Google Play. When with adb you had to type adb connect IP:port, you now fill in the IP and and port under Your Watch IP Address and press CONNECT.
Instead of adb pair IP:port code, you now have to press on Wireless debugging and fill in the corresponding values.
When connected you can use “Sideload APK file” to install an apk. You can also give Juggluco permission for the floating glucose by pasting
pm grant tk.glucodata android.permission.SYSTEM_ALERT_WINDOW
above “Run Command … ” and pressing on “Run Command Only” or “Save and Run command”.