VLC can probably be skinned out like this. The image posted already resembles the default full screen controller setup for VLC.

Not the same thing, but this is what I use with mpv: https://github.com/tomasklaen/uosc

Joke answer: get the IINA devs to release a Linux build.

More seriously: MPV is pretty close and might even be able to be configured to what you want. But seriously though. Sounds like you need/want exactly this UI, so you should ask the IINA devs to make a Linux build.

It’s not blurred, but the UI for Showtime (GNOME Video Player) looks pretty similar with the edge to edge video playback and transparent controls overlay: https://gitlab.gnome.org/GNOME/showtime

I think the only ones that do that are Showtime (which was already mentioned) and Clapper which looks even better IMO. I still have VLC installed because it has just so many other features but Clapper is really good if you don't need to do anything weird with the video or subtitles to work. I really feel you on the GUI.

Use mpv player like a normal person and stop chasing weird ui things

Like this? https://github.com/Mayurifag/mpv-dark-box

I think there is no out of the box such video players. Check plugins for mpv on screen controller, some of them may suit you. awesome mpv

IINA is based on MPV, so I would assume that with a custom OSC, mpv can also look like this.

edit: went looking https://github.com/maoiscat/mpv-dark-box is definitely not what youre looking for, but an example. It might be possible to modify this to have a blurred background instead of a black background.

https://github.com/stax76/awesome-mpv has a bunch of info about customizing mpv, with a On Screen Controller section.

Make a 2 hours video of the UI and watch it.