Ask HN: What Chat Services Don't Require a Smartphone?

Seemingly there is a way to use some sort of Android emulator for running the Android version on WhatsApp, verification is either via SMS (that your dumbphone should be able to receive or - if that fails - via voice call).

Still you will need to run this "Bluestacks" emulator (or whatever it is).

Some informations are here:

https://www.techbout.com/use-whatsapp-on-pc-without-mobile-p...

Check out https://getsession.org/

Matrix is an federated chat service, but it requires internet like most others. on the plus side it has its own standard and there are even tui clients.