>>4138107Overall I don't think we get a whole lot of new Holo art, but that should turn around when the anime airs. I'll tell you what I know currently.
Pixiv has a request system if you want a JP artist to draw something specific, but you need to pay in advance and they're allowed to decline. I can't tell you off the top of my head who's open, but it's handy if you already follow someone there.
Kawakami Rokkaku (pic related) is probably the most notable non-official JP Holo artist and probably also my personal favorite. He's done a number of doujins and you should be able to find a collection of his work easily; there is one on Sadpanda I think is up to date. Hasekura named Harvest as his favorite S&W doujin.
On the Western side, Seraziel and Nyaxxy draw Holo on the regular but they're also degenerate H-artists, the former in particular doing a lot of futa. They do Patreon/Fanbox requests but I'm not sure about normal commission work.
Deculture is a /tg/ drawfag with a pretty decent quality and high work output. I don't think he normally draws a lot of Holo, but his commissions are always open if that's what you want.
/a/ has the Weekend Waifu Drawthread, so if you go there you may luck out and get a free request.