Hello and welcome to the forum. There are many workarounds, some of them were already mentioned, but I guess it’s somewhat difficult to navigate in this long thread.
- As you have already mentioned, one of the options is to use the flashlight. There are lots of apps on Google Play, or you can use a custom Automate script, for example this one. If the battery drain is too large, you can adjust the duration of the flash and also the delay between individual flashes.
- If you don’t want to press the power button to wake up the screen, you can use WaveUp. But be aware that there are currently some problems with the proximity sensor, especially on direct sunlight.
- If you spend most of your time on a PC, you can sync the notifications using KDE Connect or any similar app.
- The last option I can think of is using a smartwatch. I personally use Amazfit Neo with a custom Automate script that periodically notifies the watch when there is an unread notification.
If none of this suits you, then FP4 is probably not the right phone for you. (And that’s absolutely okay.)