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.
Apple will accept genuine Apple Battery Pro Max for the same price as the phone itself.
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”.