Idk I used the PVE community scripts (formerly tteck, may he RIP), and I just had to point it to my smb shares, then add it to my reverse proxy, and it just worked since.
I've had a problem the other day where it wasn't working anymore but that was 'cause it had filled its 8Gb disk allocation.
I think because it's got a black background in the UI and it makes people feel like hackers. OpenMediaVault's choice of white and light blue is way less 1337.
I was put off by the immutability too, as a long-time Linux user, but it turns out it doesn't really make much of a difference. You just install things slightly differently, the biggest drawback so far are the interoperability issues with flatpaks, 'cause, you know, sandbox and all, but it's really minor tbh.
On the other hand it's very polished and convenient for most things, so much it converted me after an eternity on Fedora.
I mean, after the swastika, SS logo and iron cross, it's like the fourth most famous Nazi symbol