I think in the US I’ve heard ETF/ACH transaction fees are usually around $2.50? It might be possible to have that apply across a batch, though, as in if you submit 10 payments to 10 different people as a single transaction it’s still just $2.50, or 25¢ per person. I’m only getting this from hearing accountants complain at companies I’ve worked with, so I don’t understand the details. But I’ve seen it pretty common with companies doing payouts to want to see a minimum amount before they actually send the payment, otherwise it’s not worth doing.
GOG is pretty good because of this. I check in there if I’m considering buying something on Steam. There might still be compelling reasons to buy on Steam, like I bought Parkitect on Steam because a review on GOG specifically called out how the mods really only work well on Steam, but I’m at least checking first and maybe Wishlisting the game on GOG. I have fairly reasonable trust in Valve while Gabe is running it, but I feel like I can have longer trust in keeping copies of installers myself.