The credits / google offer up a "Caresten Wieland", but that's either a pseudonym or the name of a member of the developer team who took credit for someone else's work, because the Lula games are all that "person" was ever involved with. Any idea who the artist actually is / where I can find other art by him?

Character designs were done by German comic artist Carsten Wieland.

I don't know of any non-game related work but there is plenty of Wieland artwork in a lot of other games.
There is some information on mobygames, but it's not really complete.

Some of this artwork was featured in early/mid-90ies Amiga and PC Games. I know of these titles that were made that had some Wieland graphics: Dime City, Bazooka Sue, Hollywood Pictures, Chewy - Esc from F5

Lula was made in the later 90ies by his "Interactive Strip" - company. They did other little games based on that Lula character. Wet Attack: The Empire Cums Back (1999)
Lula Flipper (1999)
Lula Inside – Lula als Tamagotchi (1998) / "Lula Virtual Babe"
Lula Strip Poker

This was softcore stuff. Later, Interactive Strip changed their name to "Redfire Software" and put out hc titles for the adult sections of video stores that were often released in cut versions for the mainstream market. They eventually disappeared years ago. Not all of these contained much of Wieland work, some were 3D-based games.

Titles prominently featuring Wieland toon style artwork:
Airline '69
Airline '69 - Krasser's Revenge
Ibiza Poker
Patti Pain's Bondage Poker
Juicy Lucy
Inside Chessie
Ibiza Babewatch

I guess I'll have to warn you before that some of these are not exactly high quality. At least for me, it's really usually just the artwork that still makes them enjoyable in some ways sometimes.