To be fair, while not all early access titles actually follow this rule, Steam does in fact have a rule that early access games are not to be reliant on the income of sales in order to continue their development. Using the income of sales to develop it better/faster on the other hand is entirely acceptable, they are just intended to be able to fund the base game as initially planned without relying on the sales in early access. (Again, I am fully aware that not all devs actually follow this rule and there seems to be very little in the way of actually enforcing it unless a game is overwhelmingly reported to Steam...and considering some of the abandoned BS early-access micro-transaction filled crappy games i have sitting in my library I am aware it can be surprisingly common to).

Valheim though, is a surprisingly well-polished early access. Some of the mechanics they choose to go with, or how they choose to execute them may not entirely be to your tastes, but those mechanics at least function as intended the vast majority of the time. There's no micro-transactions and honestly i dont even currently see a way that they could or would realistically implement them (plus I have heard no news about any plans to do so...but im also aware that things like 76 do exist where they claimed their wouldnt be micro-transactions that altered gameplay, only cosmetics, and then decided that was a horrible financial idea later). As it is right now though, the closest you get to anything remotely resembling a micro-transaction is the merchant in the game (for context, no he doesnt take irl cash, just in-game treasures/gold you find abundantly as you play already...that's part of the point I was making).