Heard from several modders that NPC assets and player assets are 100% incompatible. Perhaps Redmod can change something about that as was stated by the REDs that it can utilize animations?
Eitherway, you're better off asking around on the game's modding Discord.
I think the biggest problem is animations since some NPC might not have the right one so there will be a lot of morphing etc but replacing the mesh should work. You can look it up here: https://wiki.redmodding.org/wolvenkit/readme
Redmod changes nothing really on the actual "creation" side. Practically speaking; it's a hook, built around a command line tool or extracting and packing assets, so that Redmods that can be turned on or off at launch. Nothing can actually be done IN Redmod. There really is little reason to be hopeful about it. It's barely more than a repackaged CP77Tools.exe. I don't say that as an insult, but to make it clear that there just isn't much "there" there. How they intermittently tout this as a game changer is a bit distressing honestly.
Big mods that can significantly add or change things in a Bethesda way aren't being updated/built now for two reasons;
1 - No one knows what will change given the progress and announcements. 2 - It's a hassle to add anything to the game for players, and can be rather difficult just to change things... Some things we still can't change, even seemingly simple stuff like environment settings in specific regions. For loading scenery changes you have to have, using assets already in the game mind you, multiple extensions then open the GUI, go through a few menus, select the preset and then reload the game. Sometimes the replacement won't load either, or you'll have to do this all over again each time you fire the game up, including character swaps. That's not very fun at all. We're not going to see 2077 become Skyrim unless serious tools from CDPR are released.