FH is a game that, at it's core, is kept alive by it's users and people who, through all the roughness, have managed to keep it up and running. FH should not become a game that has to milk it's users for cash to stay alive, but in order to make the game better, money is key.
I have three ideas as to how money could be brought into the game.
FH has a community of very creative and talented people and that is something that can absolutely be used in the game's favor! A marketplace for users to sell their handmade presets, items, animations, bodyparts, markings, or even whole maps for cash or (some kind of ingame currency) could bring a much needed cashflow into the game if the devs get some cut of the sales. However I would not know what kind of rework would be required for such a marketplace, but it would have the benefit of making aesthetic mods an officially supported feature in-game.
Allowing players to donate towards the game is also an option, no amount is too little to keep this hole-in-the-wall game alive. The devs setting up a Patreon would also be about as helpful.
Ads. You, me, and everyone who has ever used anything that is free to play has encountered adds in-game, and we all absolutely hate them. But ads are ultimately a necessary evil and can be implemented in ways that are out of the way and minimally irritating.