If you intended to attach photos to your inquiry, unfortunately we did not receive them. You're welcome to try again, but images will need to be very clear and well-lit (and ideally include a ruler for scale) so we can try to ID something that small.

Fruit flies, and any other type of fly, need a source of moisture for their larvae to live in. It doesn't need to be open water, like tiny puddles that can harbor mosquito larvae, but it does need to be something damp, like residue lining a drain (for drain flies), organic matter below a house (for phorid flies), or fermenting fruits (for fruit flies), as several examples. Excrement from fruit flies would probably not be as noticeable as what you're describing, but if you're not seeing any adult flies of any type, than it's probably due to some other cause.

Miri

A larva (maggot) develops into a brown cylindrical (or rice-shaped) pupa before emerging as an adult. The non-moving pupa is usually not far from where the larvae were feeding, since they don't crawl very far (especially on dry surfaces). A sample image of its shape (only a couple millimeters long or so) is on the linked page. We doubt they would be formed on and attached to a bathroom wall, but it's hard to tell. Yes, freshly-emerged adult flies would need to expand and dry their wings after emerging from the pupa, and only the empty pupal shell would be left behind. If needed, a pest control professional should be able to ID the insects (either in person, or by bringing samples to an entomologist).

Miri

You're welcome!