I assume you are not in the US where they do all feet and inches . As for the lighting I like 4" pots 4000K LED bulbs and you put lighting where you need it so usually above the toilet . in the center of the room one above the shower and a nice bathroom bar light above ythe mirror all the same bulbs I never use dimmers in bathrooms or kitchens but nice to have different lights on seperate switches in both spaces .Maybe 2 pot lights one over the shower and one in the space next to the shower that is empty in your drawing or is that just a big shor and in that case still needs 2 pots.

Make sure the bulbs you select do not conflict in color.

Thanks @kandrewspa, @BeverlyFLADeziner & @Patricia Colwell Consulting for the advice, much appreciated.

Just adding a couple of details, the mirror is a double-door cabinet, does have lights on the side it, so there is a niche between the mirror and the sink, but would not have (and no room for) wall mount lights.

There is also a shower heater light that is super bright in the middle of the shower room, but only will be used for very cold days, so that puts some extra challenges, as I don't know if I should put another LED light to above the shower niche or end of the shower, it feels weird to add to the center of the shower as that has the heater light already.

I'm adding a rendering for reference, I thought of placing 5 recessed LED lights as in the drawing below, but like some of you said, that might be too much, if I reduce it to 2-3 the shower niche and cabinet might not have much light. Also, is there a rule for how far away the light needs to be from the mirror/wall to be ideal, and would it be a bad idea to have a light right above the rainfall shower head (concern about the reflection of the metal)?

"it feels weird to add to the center of the shower as that has the heater light already."

You can install a 2" LED light such as this Envirolite EV26081WH30; it will hardly be noticed. A wafer light such as the Juno WF2RDALO25SWW5 would be even less noticeable.

"would it be a bad idea to have a light right above the rainfall shower head"

Yes, I made this mistake and disconnected the light.

"how far away the light needs to be from the mirror/wall to be ideal"

Far, far away. I would not put a recessed light above a sink, just use a vanity light or sconces.

I wouldn't position a light over the toilet...or the person sitting on it.

A couple of recessed lights along the centerline of the room should be adequate.

Don't forget dimmer(s). Lutron LED+ dimmers are the best.

Thank you @wdccruise