Also note that if it’s just for personal use, you don’t have to have a domain for HTTPS. You can self sign, or create your own certificate authority, you just need to clients to trust it. But domains can be cheap or even free, so it’s better to get one so you don’t have to specially configure your devices.
Abrechnung is really good and actively developed and improving. The UI is already pretty satisfactory, and there’s also an API which is needed if for example you want to bulk-import a spreadsheet, for now you have to code it a bit.
Piper is my choice. Very easy to use from the command line, fairly good sounding voices. Prior to that, for years (decades?) I used espeak-ng, had a very robotic voice but articulated almost everything very clearly, and I got used to it so didn’t actually mind.
It’s a way for the vehicle owner to broadcast to the world that they have a small dick.