Hi everyone, I had the same issue and want to share how I was able to get it to work. I have a redmi note 8 pro.
I only used: Galaxy Wearable and Galaxy Watch5 Manager from google play directly.
Changed the permission of both apps to grant everything, also check the start automatically.
Then I opened the Galaxy Wearable app and click search, pared the watch (in my case it asked multiple times to pair after the 1 one, just clicked cancelled).
If the Galaxy Watch5 Manager does open itself, click on Overview( the square button) and tap the app. Took me multiple taps to get it to open. I had it get stuck on login to Samsung, if it happens, just close it and pair the Bluetooth from the phone directly (not using the wearable app) and it should open again, or tab the app is the overview till it opens.
From here I just clicked no to every option (removed the tick in the check-boxes), no login, no sending data, no gps, no internet, only clicked approve when given no other option. This is important because I tried all combination, and this was the only way it ended up finishing pairing with the phone. After that you can modify this any way so you are not loosing on anything really.
Sorry that I cannot give a step by step guide, It took me two days to get it to pare. Hope it somehow helps someone