Light Bicycle can make a rim brake version of many of their rims if you ask them to specifically. I think they use a graphene brake track with a grooved surface. It doesn't come that way by default. This one might work:
RM29C06 Carbon MTB Rim - Light Bicycle
I might do it in the future on this 26" rim when my current rim brake track wears through because I can't find any aluminum rims that I like in 26".
RM26C02 Carbon MTB Rim - Light Bicycle
Underneath in the comments someone asks:
Hello, Do you think there is enough interest in making a rim brake version? I would really like some carbon rims for my vintage bike. Thank you
Hi Brent, It is okay to manufacture this 26er bike rim with rim brake version. We just sent you quotation through email. Please check. Thanks, Lightbicycle
Here's a road wheel that has the rim brake grooves they use. It's wide enough for you, but heavy and you probably don't need the aero shape:
AR56 Carbon Road/CX Rim - Light Bicycle
Carbon wheel and rim brakes have been use for years for muddy cyclocross. I don't think it's a problem. In my case, I stay out of the mud anyway.
Lots of QR hubs are still available, and also lots of choices for hubs that can convert between QR and thru-axle. Here's a budget hubset with DT star ratchet (non-EXP) compatible parts (54T might not be reliable according to this thread DT Chinese 240s (ZTTO M1 Boost hubs) | Page 3 | Mountain Bike Reviews Forum (mtbr.com)
, but can swap it out for 36T DT units):
ZTTO NEW Ratchet 54T Disc Brake MTB Hub 32H 32 Hole Thru Axle Quick Release XD HG MS Ncleo 142 12 100 135 Sealed Bearing|Bicycle Hubs| - AliExpress