On Watch 6 and after the update to Android 13 on Watch 4 and 5, connecting via adb has become an even greater challenge: To connect you always have to add a port number and, in my case at least, I couldn't make a connection before first pairing the devices.
In developer options you turn on ADB debugging and press "Wireless debugging". In this sub menu, you turn on "Wireless debugging" and press "Pair new device". It will show a pairing code and the IP of the watch and a port number. On the computer you type:
adb pair IP:PORT NUMBER
Where IP is the IP of you watch and PORT the port shown on the watch and the NUMBER the pairing code shown on the watch.
here after you have to press
adb connect IP:OTHERPORT
IP and OTHERPORT are shown in the wireless debugging subscreen on the watch, under "IP address and port". On my case OTHERPORT was different from PORT used during the pairing.
here after you can use adb
adb -s IP:OTHERPORT install -r apkfile
where by apkfile is the APK to be installed.
