I completely concur with Marcus here - and have seen the same dynamic play out in several communities, especially when involving those who are less deeply in the Discourse ecosystem.
The Calendar subscription URLs for external calendar apps is absolutely brilliant for engaged members of a Discourse site. But it does fall down for those on the edges / outside.
I’ve mucked around with this in the past, and found that I could modify the downloadable .ics to make it behave as @pacharanero desires when emailed as an attachment in a PM. I don’t seem to have collected my thoughts anywhere useful though sorry.
In the first (and achieveable) instance, it would be great to have the existing .ics file (with a few tweaks) easily PM’able.