

For ditching Signal on mobile, you can use Flare, an unofficial Signal desktop app built from scratch, which supports setting it up as the primary device. It is recommended to use the Flare in conjunction with the official Signal desktop app so that you get all of the features without compromises.

You could use a VOIP provider so you can do calls and SMS from your computer without needing a SIM. An example provider is JMP.chat, which could then be used with any fully featured desktop XMPP app, like Dino or Gajim.