I use deadmansswitch.net - it sends you an email to verify that you are still alive, but you can also use a Telegram bot. In this case I have it set to send a passphrase to an encrypted file with all of my information to trusted individuals.
It's completely open-source and you can self host it.
I mean, seriously, it isn't a laughable idea that a bomb that will explode unless you poke some button every 24 h might eventually explode even though you weren't incapacitated and dutifully pressed that button. I'm not even considering the case that you might have been temporarily incapacitated. People wouldn't call you paranoid if you say that carrying such bomb is a stupid idea.
As technology advances, we will develop more effective means of determining whether someone is truly deceased, for e.g. something like Neuralink could provide significantly improved methods for verifying actual death.