I meanwhile switched 7 sites to ClassicPress and here are some plugins that I can cornfirm they are working:
FoooGallery
FooBox Image Lightbox
GDPR Cookie Consent
MetaSlider
Nested Pages
Timetable and Event Schedule
I also contacted updraft (MetaSlider) if they would support ClassicPress. Here is the answer:
New comment on your idea “Support ClassicPress”
Hi,
I don’t see any reason why we wont. I guess it would depend on the direction they take the platform in. Let us know if you run into any issues and I’ll see if it can be resolved.
Permalink to the comment: https://www.metaslider.com/feature-requests/feature-request/support-classicpress/#comment-22977