I’m encouraged that you aren’t planning to put impervious flooring on the slab of your room. Not doing that, you have dodged a bullet IMO.My father in-law had his cement slab in the garage ground and polished, you can eat off it. I don’t think it was sealed.
Regarding paint, many products claim to "seal" concrete with epoxy or paint. I would not use them, because it is so difficult to effectively "seal" concrete or brick against water and water vapor.
That was over 30 years ago, it’s still the same today and still shiny. Only problem is when I go there to do oil changes, the car ramps need rubber sheets under them or they just slide away when you try to drive up them.
Cheers George