I use ITCTraining which is Flir's training division. There are others out there. I would recommend in person if possible. They have some free basic Thermography classes if you sign up for a free account. I attended the sUAS Aerial Thermal Cert class. Have also attending the roofing class and am waiting on the Level II Aerial coming out soon. It is NOT for beginners. IMHO. It covers all the concepts from Start to finish, but you have to have some basic background with Thermal dynamics. @Outts Control gave me some great advice a couple years ago when I was about to attend. He relayed the same information I am. it is not a start to finish for folks with no knowledge. As a result, I paused my class for 6 months, bought a C2 handheld from Flir. Took hundreds of Thermograms of anything and everything around my house. Used the free Flir Tools app and learned how to Thermally tune and understand what I was looking at. I then took the class and got much more out of it. there were some in my class that had no previous knowledge. They had trouble following along. This is a science, not a simple class with a cert. If you are willing to invest the time gaining experience, knowledge and background, you will be confident providing analysis and summaries to your Clients and can make money.
As for tracking animals. The biggest question is what are the environment variables? Like Delta T. The greater the difference between your SOI and the background, the longer you will have an opportunity see the target. If it's 30 degrees out, one scenario, and this is only a guess, is you could possibly successfully identify the SOI for hours. The closer the deer gets to the background temp, the less likely you will be able to identify it. 10 degrees between subject and background I would guess would be fairly easy to see if in plain view.
Your Xt sensor does hold temp values, but only the 40 percent around the center of the image.