wrote a little timer app for covid selftests (only 2 years late), with a pre-configured 1 minute (Biosynex swab sitting in the buffer) and 15 minute (lateral flow soaking, same for lots of brands) timer
has a manifest too so you can install it as an 'app'
it will also keep track of the time if you accidentally close it, but you do need to reopen it for the alarm
time to actually use it for real