I recently used Spike (https://www.spikenow.com/), both desktop and mobile app. The I switched to Spark. Its probably not easy without mouse. And I also did not like the function that they automatically includes a tracking pixel to the mails. Anyways you may take a look.

BTW for private mails I use paid version of Tutanota with own domain, because of privacy aspects.

You could try Mailmate (https://freron.com), I think it ticks all your boxes. The stable is old, the beta is located at https://updates.mailmate-app.com/2.0/archives/