it is a development machine with highly specialised tools - Altium Designer, SolidWorks, IDA Pro, Altera Quartus, etc.
Upgrading the OS is not a trivial thing as would be on a phone or tablet. Also when upgrading the OS it would make sense to upgrade the HW as well, and that is a major investment. And Signal is just not important really to warrant that.
I would still use it on my phone though, but on the PC is just Viber unfortunately (whatsapp dropped as well).
sorry, to hear that happened to you! I have paid VPN and use it to isolate devices on my network that i don’t trust (not torrenting).
I would never trust 100% a vpn running on the same machine as the app that needs the connection.
Probably super paranoid, but always use one of those VPN boxes with separate ethernet sockets - for input and out connection. Quite cheap on Amazon. I assume they run Linux and when they loose the VPN just crap out instead of exposing my home network.