I used a tinted hardener that is worked in after the initial placement and leveling (when power troweling). The floor looks like it is painted (except it isn’t, so nothing to flake off) and for small scratches they don’t really show as it scratches to the same colour. The surface is very smooth (I really like it) - the guy doing the slab claimed he was supposed to use a brush finish so it wouldn’t be as slippery when wet. He absolutely understood that there was no way that I’d agree to a brush finish, as long as it was on the work order for a smooth finish at customer request - then he was satisfied and made it nice and smooth. I also bumped up the cement ratio a bit and had fibreglass chop added to the mix (the concrete is stronger than the bare minimum and less tendency to crack). In the 15 years since building the shop, there are a couple small cracks - overall I have been very satisfied.
I think a sealer may also have been applied (a couple weeks after the pour). That step is fuzzy in my memory.
There are quite a few things you can do with a slab, during construction - not so much afterwards. Continue doing your research for what is available and suitable in your area. I went with 2” of underslab insulation that had the formed tubing grooves, and put in hydronic loops, then rebar above that. The target thickness was 6”, but strictly speaking it ended up at 5” (which has turned out to be fine) - even though I have machines wherein the manual says to have much thicker concrete (have 3 machines at 8000 lbs). I also put in some in slab conduit for wiring. The machine plan and wiring requirements have changed a lot since I built the shop, but having a few in slab wiring options has been really handy.
I found that the various extras cost very little to add during construction (and basically impossible later). A couple of the contractors I had working on the shop commented that people building million+$ homes will go as cheap as possible (except for bling in the finish details).