I haven’t seen anything that meets your requirements.
Is there a chance that you could find an open source keyboard and a translation layer, like a software or an input card? I know it’s not ideal, but worth investigating.
Best way to make the switch is by immersion. I’d also like to add it’s best to do it when you’re not being forced on a timeline, and you have time to deal with it. All my personal machines made the jump 7 years ago and I don’t regret it.
Because they killed google podcasts and moved it to YouTube music before they had basic equivalent functionality ready.