I had a look and found this app, but it’s not FOSS (as far as I know) and it says it won’t work on my phone because of the Android version. Sharing just in case, but I realise it’s probably not going to work for you either:
@sanguinepar@BeatTakeshi have you tried looking it up online? maybe it has an official website. Lawnchair had the same issue but had an official apk on their website.
I had a look and found this app, but it’s not FOSS (as far as I know) and it says it won’t work on my phone because of the Android version. Sharing just in case, but I realise it’s probably not going to work for you either:
https://play.google.com/store/apps/details?id=com.trendy.frontflashnotification
EDIT - another one, but this time it would work on my phone, so hopefully yours too. Still not FOSS though, sorry:
https://play.google.com/store/apps/details?id=com.ledblinker
@sanguinepar @BeatTakeshi have you tried looking it up online? maybe it has an official website. Lawnchair had the same issue but had an official apk on their website.