Firefox, something Firefox based or something entirely other?

Want to learn/try one of the two alternative Keyboards for Android. Which do you prefer, have had the best experience with?

I have a new Phone Plan starting in a couple of days. I have the option to choose a Physical Sim or eSim, both are similarly easy to get going. What are some +/- of both, what should I use? Or does it even matter at all? One thing I think of but have no conclusion to yet is when my Phone gets stolen, is that a concern then?

I've been using China/Xiaomi Phones for the longest time and hated the installed Android Version because all of the clutter, bloat and privacy concerns. Now I am about to buy a Google Pixel 7 Pro. What do you guys think, is a Custom ROM needed or should I just stick to the Default with Adguard and Disable some Google Apps to get a similar Experience? Just hoping to get some Opinions. :)