Hey, so this is just my 2 cents on the FM Radio issue:
You require a proprietary MediaTek Java Native Interface (JNI) in order to actually connect/interact with the FM radio hardware, and that does not automatically “register” on AOSP which is what /e/ and Lineage use as its base. These can be manually added to AOSP, and what we did internally was to remove such classes that were of no use, but then the entire registration functionality didn’t work at all.
On the unified firmware (11.0.0-11.0.2 for zirconia) we faced the same issue, but then we ported over the interfaces and libraries required successfully, and STILL did not get FM radio working. Turns out, MediaTek requires a few routing quirks to the audio output devices and we didn’t have those hooks.
We then used this patchset https://review.lineageos.org/q/topic:eleven-mtk-fm and got it working on unified. This, in the same way, will be shimmed out and ported to AOSP very soon.
About @ecs 's question, yes you can root with the boot image method.