Customizing your boot video that shows up when you turn the Steam Deck is one of the most entertaining things of it outside of gaming. What are your favorites?
Minimal Glitch Zero 3D from the Animation Changer add-on for Decky. It's quick and looks cool. I had one that mimicked a 90s desktop boot sequence but I found I was skipping it 90% of the time since it was like 30 seconds long. Plus I think I just got over the idea of novelty boot animations.
As for myself, I'm using the Matrix one, the Neo-geo one, the Game boy one, one of the videos with the turrets (not the official one, just their red light and "Helloooo" played), one that replaces the Steam logo with Aperture's and plays its jingle, the one about history of handheld devices and one based on the PS1 boot screen. (You can play a random one each time)