Apple Watch 4 history activity data with new iPhone, old phone dropped in the sea.

I dropped my iPhone X in the sea 20 days ago water entered, I cleaned it, dried it out for 3 days before trying to start it up but it's dead.

I also have not been able to try to get it fixed and also wasn't able to buy a new one since the small island in Thailand I'm on is on Covid-19 lockdown.

I had an old iPhone 6Plus so I took my SIM card and started using the old phone, connected it with my Apple ID but said no to use available backup. I was still hoping the iPhone X would wake up. Big mistake. I forgot to turn off iCloud back up for the iPhone6 plus and it appears that after a few days my iPhone X iCloud backup is gone. Apparently iCloud keeps only the 3 last backups.

I kept exercising using my Apple Watch 4 but didn't pair it with the old iPhone. The iPhone 6 cannot use the Activity app (that came with 6S) so I figured I just wait until I get a new phone delivered.

Today I got a new iPhone 11 Pro Max and I'm really hesitant on getting started. I know a couple of people that lost all data from their work outs, years of it, by doing it wrong.

QUESTION: Is the Apple watch data in the cloud backed up separately from the iPhone back up? Then it would be reasonable to assume I can find that watch backup again?

I can't unpair my watch and phone, what if I can't pair with the new phone? If I erase the watch completely and then pair with new phone, am I sure to be able to get back all Activity data etc. into the new phone or is that gone with the iPhone X's backup?

My health app shows also the year old data from the watch, will that stay intact?

I share my activities with a friend of mine and he keeps getting updates on my workouts even though I haven't got the watch paired with any working phone atm.

I would so much appreciate if someone has any hints as to how to do this the best way.

Thanks, Michael