Does this webapp generators support CSS and JS injection?

Hi! I want to know, can I use some security features similar to LineageOS.

1. "Protected apps" - run apps after entering PIN or something
2. Phone encryption - what about this on Ubuntu Phone?
3. Different browsers (is there available any other, than system?), or the ability to run simultaneously one browser - this isn't security feature, but it has security capabilitiles (like Containers in Firefox)

Since camera and wifi fixed on OPO I plans to switch to Ubuntu, but want to reproduce as possible what I has on Lineage.