There's actually way less RNG that you think. The game probably uses something like the internal framecounter as a seed to randomly generate the levels. If you reset the console/emulator and start the game on the first possible frame every time, you get the same level layout every time. Depending on the level you have a 1-4 frame window to press the start button to get the same first world (I'm still not sure about the later ones, it's a little bit wonky).

Here's a video on USA-NTSC:

As you see, 683 is the first possible frame to start the game. 684 and 685, as shown in the video, result in the same first stage (and following stages) wether you press buttons in the intro cutscene, skip it, or do nothing at all. 683 and 686 are different stages. That said, the stages are not truely random, but build with certain rules. 1-1 for example always has 8 additional non-destroyable blocks on the grid, 33 destroyable blocks, 3 Choppers, and 3 power-ups: 2x Bomb, 1x Explosive Radius. 1-2 is built similar, but with 2 Choppers, 2 Orbs and 2 power-ups: 1x Bomb, 1x Roller Skates.

That said, I'm still testing out stuff. I think there's a lot to learn about this game, especially for speedrunning it. The time can probably still be pushed down a lot.

Greetings -Gerson

This is very useful and helpful Thank you for putting this up, I encourage you to keep running the game your run was great until final Boss. I might still try and bop u so watch out! I am not the best at testing out and finding new things so that would be awesome if you can find some new useful stuff for Super bomberman speedrunning.