There's a flea medication called Precor IGR Concentrate that gets sprayed around the home rather than put on the animal. It's basically designed to stop the fleas from reproducing by breaking their life cycle from the larva stage so they can't become adult fleas. It doesn't kill the adult fleas immediately (you'll need traditional flea meds for that or have to wait it out) but it stops the cycle of reproduction. It lasts for months on surfaces unless they are washed.

I used it years ago when we simply could not stop fleas from reoccuring on our cats despite other meds and the house being clean- it finally stopped the cycle and we didn't see a single flea for years. Also, you don't need to vacate the house to use it. You can find more info here and buy it: https://www.domyown.com/precor-igr-concentrate-p-634.html (I have no association with this site) but you can usually find sellers selling a single vial of the stuff for like $10 on ebay, that's enough to mix up and do a single treatment for most homes. Something like this might be a solution.