where can I find the roadmap (expected date when a compatible version will be available?)… or maybe the current version works with WP5.8?
I don’t want to have to live with the update to WP5.8 at the top of the page for the next 4 months. I have held back upgrading until I know that all is ok.
Both MainWP plugins (Dashboard and Child) show that they have been tested up to WP 5.8. You can trust MainWP to be compatible with new WP versions. And in doubt you can check this site if issues are posted, because that would happen quite fast.
WP 5.8.1 is a minor update that only fixes known issues. It doesn’t introduce new functionality, so it should be safe to install. And of course you should read the changelog or release post if you’re still not sure. That’s the best to do for every update!