Yes, it gets synched just like any other file inside my Nextcloud. However, if you have to often change the data inside, it might not be a suitable solution, since the file has to be uploaded as a whole. If it's a big container, it might be cumbersome to upload a few gig each time you make a small change.

Yes. Cryptomator is better in this regard.

I will have to take a look, thanks for the recommendation.