MergerFS and SnapRAID could be good for you. It’s not immediate parity like with ZFS RAID (You run a regular cronjob to calculate RAID parity) but it supports mismatched drive sizes, expansion of the pool at any time, and some other features that should be good for a media server where live parity isn’t critical.

Proxmox and TrueNAS are nice because they help manage ZFS and other remote management within a nice UI but really you can just use Debian with SSH and do the same stuff. DietPi has a few nice utilities on top of Debian (DDNS manager and CLI fstab utilities, for example)but not super necessary.

Personally I use TrueNAS but I also used DietPi/Debian for years and both have benefits and it really matters what your workflow is.

Docker or LXC containers won’t hurt your performance btw. There’s supposedly some tiny overhead but both are designed to use the basic Linux system as much as possible: they’re way faster than on WSL. For hardware acceleration it’ll be deferred to the GPU for most things and there’s lots of documentation to set it up. The best thing about docker is that every application is kept separate to eachother - updates can be done incrementally and rollbacks are possible too!