Welcome to Texas
AFIK (you will want to verify for yourself): You can do inspections that do not fall under the jurisdiction of TREC or another state agency. Theoretically you could do infrared inspections. However, TREC considers any inspection related to the sale of a property, whether for buyer or seller, to be under their jurisdiction, so I wouldn’t be sure that they would not consider your thermal work to be under their jurisdiction. I personally would not think it should be under their jurisdiction, but my opinion doesn’t matter at all to TREC. It is my understanding that they sued a well regarded stucco specialist some years back for not having a TREC license and he won, but it cost him a lot of money to do so.
You should be able to do home check-up / maintenance and 12 month warranty inspections all you want so long as they are not part of a real estate transaction.
Texas, does not require licensing for general Indoor Air Quality testing, but they do for mold, asbestos and lead, so be careful to stay on the right side of their licensing reqs. The Texas Department of State Health Services controls these licenses.
Termite inspections require a license from the Texas Department of Agriculture.
P.S. I just went to Wyoming last October to go Pronghorn hunting. It’s a beautiful state.