Does anyone have an idea if you were to enable wifi and register a MS account exactly what data is being sent to them? Do they send your MAC address? Obviously

Does anyone have an idea if you were to enable wifi and register a MS account exactly what data is being sent to them? Do they send your MAC address? Obviously your IP address and I assume during account creation they would want your phone number/alt email? I can see Windows not being accessible as some places genuinely don't have internet, and if they do, it's heavily restricted. I've also heard if you enter something like "a@a.com" or a banned email during setup it can let you through? Obviously this is a way of 'legitimizing' consent to data collection and it would be very interesting to see a breakdown of every byte of data MS gets sent (even file explorer communicates with a US IP address). I genuinely think the EU needs to take a look at this, I would be very surprised it this wasn't abusing their monopoly-like position for mandatory data collection (although, they probably welcome it!).