My company uses Roundcube for Webmail and offers Thunderbird as a native client. It’s always great to see free software in a corporate environment.

Yeah it’s really cool. Also works very well with an external Gpu.

Buy Framework laptops, these have amazing repairability and upgradability, as well as good Linux compatibility. They even offer ChromeOS options, if you ever need a Chromebook.

Roundcube should work pretty well for you: https://roundcube.net/

What part of Windows (or Microsoft software in general) is not a data collection service?