I recently read that devs officially added Blood Infusion, Cursed Blood infusion, Oil infusion and Cursed Oil Infusion to be used for summoner Incarnate.
There is no mention on the Divinity 2 pedia about these skills and i was unable to find a detailed patch history from 2019 for Divinity 2 to check has it been officially listed anywhere.

I tested it myself (only had minor mods and larian gift bags enabled like Crafter Kit and Pet Power) so its definitely a part of the official game:

Blood Infusion (summoner book + necro book)
Cursed Blood Infusion (source summoner book + necro book OR summoner book + source necro book)
Oil Infusion (summoner book + geo book + oil barrel)
Cursed Oil Infusion (summoner source book + geo book + oil barrel OR summoner book + source geo book + oil barrel OR source summoner + source geo + oil barrel).

KEEP IN MIND NOT ALL SKILL BOOKS ARE VALID FOR THESE RECIPES!
For example i could not make any of these using the Inner Demon source summoner book.
Try with several different books from the adequate spell schools - it will work.
Enjoy your new Incarnates

Just to make it clear these new Incarnate infusions seem related to the official Larian gift bag called Pet Power so you will have to enable that in the main menu (after you start/load a game).

I don't think so. I don't believe I activated pet power (unless I did it accidentally) and I still had those capabilities. What I don't recall is if they worked when using a regular incarnate in, say, cursed oil. I didn't use infusions other then far-sight and power very often - I just created my incarnate on the desired surface (fire, oil, water, etc).

I wish that oil and blood infusions would be added to the base game. The gift bag for summoners changes game balance, so I'm stuck retarding my summoners' initiative to ensure that someone else can land blood first.

Do we know if Larian is actively patching this game, still?

You can get blood infusion (or oil) if you cast incarnate over appropriate surface ...