[AU] Any gotchas replacing cellular iWatchS3 display?

Hi,

My FiL fell and shattered his 42mm iWatchS3 display, I switched it off and carefully removed the display, I left the battery connected and the force sensor appears to be intact all the flex cables detached no problems.

So I'm trying to decide whether to get the relevant display from AliExpress, or put it in the too hard basket.

So my concerns:

Is there some sort of cellular radio difference that I need to watch out for, I'm in Australia, I assume the eSIM data is stored on the watch and that with the new display cellular data will "just work"?

I need to check if he uses Apple Pay (NFC) as I believe you lose that unless you transplant the NFC over from the smashed screen, any transplant instructions, I found a video with hot air and soldering four tiny jumper wires, yikes, he might have to do without Apple Pay?

https://m.youtube.com/watch?v=6To9gMYVT0...

Will the watch lose its waterproofing?

Should I replace the battery at the same time as it's over 5 years old, FiL reckons the battery is still good, it's not bulging?

Any other gotchas, the video above at around the 130 second mark suggests that as well as Pay not working, the new NFC could stop the watch booting?

Thanks!