I have developed a suckless alternative to Nextcloud's Files webapp, with the server software written in C99 plus POSIX extensions and no JavaScript for the client software:
https://git.sr.ht/~xavi92/slcl
As a free software advocate and guitarist for @kovok , we decided to self-host our data into a Nextcloud instance running on a Raspberry Pi 3B that unfortunately took most of its RAM and was slow.
Therefore, we have moved to slcl. Now, I am happy to see how lightweight slcl really is!