According to MrLamaSC (a popular youtuber in the genre), it doesn't have any predatory micro-transactions, but the usual stuff. Cosmetics, increased bag & stash tabs, pets... similar to Path of Exile. Everything unlocked is account wide and all progression & content is unlocked through play.
This is of course really nice to hear, I'm a fan of the series (though the 3rd game stumbled hard), so I hope this is solid, fun and not too overly grindy. I look forward to trying it, though I'm not sure it'll replace Diablo II Resurrected for me.