That is a tough one, unless people really want to use something other than Office 365 or G Suite for reasons of ethics, privacy, autonomy or some other important reason then it is probably going to be task akin to rolling a boulder up a hill…
The SOGo webmail interface that Mailcow provides is very nice and when the DNS is configured for autoconfig and autodiscovery then local email client configuration should be painless and more-or-less automatic, see the client configuration section of the Mailcow documentation.
We picked Mailcow for our mail service a few years ago after evaluating all the other options projects and we don’t have any regrets, we do have a support contact with Servercow, more out of solidarity and wanting to support the project than for any ongoing issues, we have had a positive experience working with the developers (I have raised a few issues with the project over the last few years).