VLC has built-in support for Blackmagic SDI output cards:

https://github.com/videolan/vlc/blob/master/modules/video_ou...

Though a quick search through online forums suggest that module isn't compiled into Ubuntu's version of VLC by default, so you may need to compile your own version:

https://gist.github.com/afriza/cd9ce01a7b47b9bd3f192e95af1a0...

Not sure about VLC, but ffmpeg has great support for Blackmagic, you just have to download the Blackmagic SDK, compile ffmpeg with Blackmagic support (and the SDK in path) and then you'll have a separate input/output device available in ffmpeg. The other great thing about this approach is that this way audio also takes a dedicated, integrated path, bypassing OS layers and maintaining sync with much less effort.

I'm not terribly familiar with Linux use of hardware I/O devices so my guess would be yes unless Blackmagic (or someone else) makes some kind of Linux kernel extension that would allow you to manually specify that or VLC has built-in support for external I/O devices.

Edit: Just checked because I was curious. The default installs of VLC do not include Blackmagic support but you can compile versions from the source for Linux that include it (if you also download the support files from Blacklink first).