

Some good advice already in this thread.
Also worth considering QEMU as an alternative to VirtualBox. The Virt-manager tool is decent way of managing machines, and it’s relatively straight forward to create a base machine if you’re duplicating it. Virtualbox is perhaps initially more user friendly for absolute beginners, but once you have any familiarity with virtualization I’d suggest QEMU offers much more.
Also I find integration between the guest and the host linux system is generally more straight forward. Most linux systems already ship with samba and other relevant tools QEMU uses to interact between host and guest. There isn’t a need to faff around with the guest-additions stuff. Plus KVM virtual machines can run with near native performance.
There is an official Jellyfin plugin that adds DLNA support; content can then be accessed via any DLNA client including VLC (built in support). MPV can also use DLNA with it’s own plugin.