Oh proton gives mobile too... Ya know I didn't feel like paying for the mail thing as I can have my domain and relay easily but the mobile thing I didn't know.
But I will be honest I didn't see it mentioned on the web, it's already a thing?
The problem here is that all of the registration information that is listed for a number (OCN, LATA, etc) allows them to track back what TYPE of number it is based on what ILEC/CLEC it's registered with and how it's registered.
This means when I put my google voice number into some things, they can come back and yell that it's not a mobile phone, or that it's a virtual number, or whatever and disallow it.
I used it in college and never had any problems, it seems to have feature parity with Excel. I used Excel professionally for a while and some of the workflows are a little different, but on the whole it's really intuitive and easy to use. I'm sure there are other FOSS budgeting solutions, but Calc works so well for me I don't see myself using anything else.