https://store.planetcom.co.uk/products/gemini-pda-wifi-only was an option but sadly they pivoted to devices with baseband only...

There's https://pyra-handheld.com/ but it's semi-existent not-quite-vaporware for about a decade already (props on the staying power of looking to get this project finished, though!)

Gemini also the disadvantage of horribly out of date software. Encrypted chat software is not a good combination with Android 8.1 missing years of security patches.

Planet Computers are probably going down the drain soonish after the fairly disastrous crowdfunding for the Astro phone. I know a friend who has a Gemini and he wasn't impressed either. However I am massively biased, as I paid for a Astro which I'm still waiting for several years after the kickstarter finished. To be fair, they have had pretty major issues with the ODM, but still we've only just found that out recently.

https://www.indiegogo.com/projects/astro-slide-5g-transforme...

I make a VoIP/WiFi phone that excludes any sort of cellular radio because that's what I want as well:

https://wiphone.io