Pretty sure the beeper app is just a fork of element with added ui for interacting with different bridges.

What happens if you just send the example selfie instead of your own? Do they actually check it?

Shooting someone is not the only harm that can happen. There are countless assaults (domestic, sexual, verbal, etc) every year that occur due to extremism such as being an “incel”. Also you sound paranoid and have offered no evidence what you say is true. If you really are being spied on by the government the only way to stop that is to destroy your electronic devices (drill holes in the harddrives), move as far as you can (preferably russia or china), and never post publicly on the internet again.

You can get prepaid sims which don’t renew automatically. You can also find carrier’s that allow you to cancel whenever no extra charge.

The cheapest option would be to just buy a cheap sim and verify the number with discord then throw the sim in the bin.