is there a way to light up a room without using torches, glowstone or sea lanterns?

There's a plenty of other light sources, than the three listed - jack-o-lanterns, campfires, redstone torches, even lava - but as I understand, they aren't satisfactory to you. Additionally, lighting one or more Nether Portals inside will produce light level 11 from the portal blocks.

Probably your best option in 1.16+ is using Crying Obsidian instead of plain obsidian for the walls. It would provide the same durability of the construction while generating light level 10, sufficient to prevent mob spawns within 2 blocks from the crying obsidian blocks and you can obtain it in bulk through a piglin bartering setup, even a simple one, you'll just need plenty of gold.

If your concern is mob spawning, another option is to spawn-proof all spawnable spaces in the construction by placing non-spawnable blocks on them. These include carpets, buttons, redstone dust, bottom slabs, bottom trapdoors, rails, double snow layers, and plenty of more. Rule of thumb: if you can't place a button on top of it, it's spawnproof; the opposite is not necessarily true e.g. glass is spawnproof too.

If you insist on plain obsidian and no light sources whatsoever though, this gets severely complicated. You'd need to light-suppress the construction of the ceiling, preserving daylight inside the bunker. The process involves first overwhelming the light update thread of the server through a contraption that generates an extreme number of light updates, so that the lighting of your bunker isn't updated as you build the roof over it, and then crashing the server before the light processing thread catches up to your roof-generated updates, and as result the scheduled update is lost, and your room remains fully lit despite not having any light sources.