> StreetComplete asked me which floor this shop was on, however coming back to it this info appears to be already tagged? I'm not familiar enough with indoor tags to know what's going on here.

We have two tags for floor level, https://wiki.openstreetmap.org/wiki/Key:level and https://wiki.openstreetmap.org/wiki/Key:level:ref

level always starts with 0 at the lowest ground level, and is always numeric, -1, 0, 1, ...

level:ref specifies how the level is referenced on signage, lift buttons etc. eg. B1, LG, G, 1, 2, ...

I find level:ref easier to survey and more useful to map as someone looking up what level something is on wants it to match what the signage says and the lift buttons say.

However level is also important for maps to make indoor maps because it gives a consistent ordering, otherwise (especially globally) we can't know the order from level:ref alone.

StreetComplete asks for and tags level and ignores level:ref which has been discussed at https://github.com/streetcomplete/StreetComplete/issues/3529 and https://github.com/streetcomplete/StreetComplete/issues/1487

Because level always starts with 0 at the lowest ground level, and some buildings use levels like LG, G, 1 you can end up with a situation where you have

level=0, level:ref=LG,
level=1, level:ref=G,
level=2, level:ref=1

And since when surveying a shop it's hard to know which level:ref number corresponds to the lowest ground level it's hard to survey level correctly.