Custom roms will have more issues with this. Manufacturers like Samsung have deals with Google and will have access to the sources more often. Custom roms won’t have this access. I personally went back to the stock Pixel rom, and rooted it to still have acces to all of my modifications through Magisk modules and such while being able to stay up to date.

So it’s hard on some phones. Lineage OS support also isn’t any indication of how hard it is to unlock. The more popular devices are all easy to unlock.

That’s just confirming it’s generally extremely simple.

Which would help how? If they are really going to make it much more difficult for custom roms it doesn’t matter what phone you choose.

Security is definitely a concern, so replacing it is recommended. I’m not sure about other browsers compatible with Chrome extensions though.

It’s relevant because it’s there. If you don’t play those parts it doesn’t mean it’s there. They put the time in other things more important to the game than transitions. Also, the engine is completely different.