What to do for our condo?

Flat paint looks great...in the beginning! We all know how hard it is (if not impossible!) to clean! My suggestion would be to start with one room at a time and repaint. If you are happy with the color just find a color that is close and put a single coat of paint in a satin finish over the walls. With a good paint and primer in one along with a similar color you should only need one coat of paint.

From working in new construction, I know that the original builder-grade paint is not enough. It only gets the bare minimum coats before you move in. I told my daughter when they were buying a new construction home that she should plan to paint asap. The good thing is that the drywall has been adequately primed, so just pick your favorite tint and finish and have fun!

You current paint is clean and light colored, so you do not need a primer. Durability is connected to paint sheen. Flat or matte paint is the least reflective so it hides irregularities in a surface. Gloss paint is the most reflective so any flaw, even the smallest, is noticeable. Flat paint is also the least durable. If it gets a smudge you cannot scrub it without damaging the paint. The only reason to use a flat paint is to hide a wavy drywall caused by the studs. Gloss paint is very durable and scrubbable but also visually excessive. https://www.realhousesofthebayarea.com/wp-content/uploads/2017/06/paint-sheen-chart.jpg

IMO, all trim and cabinets should be painted with semi-gloss for durability, but at least use a satin gloss paint. Walls in any room with high usage or water exposure (kitchen, bath & laundry) should also be satin. This includes hallways and stairwells. Eggshell sheen is great for bedroom, dining room and office.