• For front light, the Magicshine RAY 2600 - USB-C, multiple mode, reverse charging, and pricey. Bear in mind they're larger than the largest Cateye lights, and mount via a GoPro mount. You can search on Amazon for "Bicycle Headlight Holder" for a number of aftermarket mounts, for example this one. The mounts are bit fiddly, since there's a nice groove for the Catyeye mounts in the washer provided by Brompton - that needs to be replaced with a regular smooth washer. As well, a longer Brake Caliper Nut is needed since the entire assembly is now a bit thicker.
• For rear light, the Jirvyuk USB-C Smart Bike Tail Light. Cheap, great motion detector feature.

Both of the lights have rubber plugs for the USB-C port that seems to counteract dampness, YMMV. Neither interferes withe the fold.

I share your desire to only use USB-C vs micro-USB, BTW. Some arguments against Micro-USB and for USB-C that I haven't seen in this discussion so far:

• Power delivery is lower on Micro-USB, vs USB-C that can delivery up to 100W. What that means in this instance is that USB-C lights are usually much faster at recharging.
• USB-C can both input and output power. The feature that this enables (should the light enable it, like the Magshine mentioned above) is using the light as a power bank - being able to charge your phone with your light, or vice versa is really useful.