I'd like a signal daemon on all my servers for alerting which could message me via Signal. This is worth a monthly fee to me.
I know people running small businesses who would really like to have a business Signal account: an ability to send Signal messages as a business identity without tying it to some specific phone number. This would be worth a subscription even if they had to get their customers to install Signal.
Signal need to figure out what product they sell that's going to fund the privacy objective: because there's plenty and they're worth having.
Just sign up with a Twilio number (using voice call) and you can make your own bot.