When searching for support services in e.g. Google Maps or OsmAnd or whatever, be sure to use a search string(s) that will capture the greatest number of useful hits.
Sometimes one must use multiple search strings.
For example, in the English version of a map of Spain, a laundromat might be listed as "laundromat" or "coin laundry" or "laundry service" or "launderette", so try searching for "laundr" or "laund" to capture all of those.
In the Castillian Spanish version of a map, a laundromat might be listed as "lavadero" or "cuarto de lavado" or "lavadora" or "lavadero" or "servicio de lavandería", so try searching for "lavad" or "lavand" or similar to achieve greatest capture of useful hits.
You might have to experiment a bit.
Also it helps to search maps from multiple providers, i.e. search Google Maps and also search OsmAnd and search Apple Maps and ... etc.
Users of OsmAnd should be aware that one can configure the map to show laundromats.
OsmAnd/Configure map/POI overlay/Laundry/
One can also configure the OsmAnd Quick Action menu to show the various support services that one will probably need as a foot pilgrim. I added Quick Action menu buttons for lodging places, restaurants, grocery stores, food, laundry, laundry service (laundry service seems to produce results different from laundry), museums, shoe repair, health care, postal service, and quite a few others. Using the Quick Action menu allows one to quickly make POIs of interest appear and then disappear them later to reduce on-screen clutter.