Similar to Nextcloud?

Question

Data synchronization

What else is alive and developing?
Except Seafile, Pydio, Owncloud, Syncthing, Resilio.
Not necessarily Opensource, but desirable. On a Linux server. With the presence of mobile applications and synchronization for PC.

Answer 1

FileStash, EteSync, Syncloud, HRCloud, MinIO, XBackBone, e2ee
But you listed the most advanced options.
If their capabilities do not suit you, then the most reasonable option is to take one of the similar projects from github (there are many of them) and fine-tune them to fit your needs.

Answer 2

https://filerun.com/
Not open source, but free for up to 10 users.
Lots of integrations and plugins.