I think 90% chance of apple going for the EU-Specific model just like they did for Digital markets act, 10 chance of screws, 0% chance of actually popping the back cover off with bare hands.
For Samsung, 50% chance EU-Specific models 40% chance screws, 10% chance back cover tool-less removal. (Edit: typo)
As for other smaller manufacturers, probably just 50%/50% either screws or tool-less back cover removal.
iPhones are already one of the best phones around in terms of battery replacement- maybe not for DIY, but for the fact that Apple will replace your battery for you themselves for a very reasonable price.
https://support.apple.com/iphone/repair/battery-replacement
An iPhone 13 Pro battery replacement, done officially through Apple, is USD$89. They will replace your battery on models all the way back to the iPhone SE or iPhone 6. At that price I can’t understand why anyone would go third party/diy.
Even the newest 16 Pro Max is only $119 for a brand new battery fully installed officially by Apple. If you’ve got apple care it’s “free”.