It can be helpful in reducing one's thermal signature, but, as you correctly noted, awareness of the surrounding environment's signatures is critical for success. Movement may also assist in compromising the stealth, but a stationary person (e.g. waiting until the search drone moves out of range) has a decent chance of blending with the environment.
We have to wait until thermal cameras drop further in price, and then hack with them, play with the thermal camo tech in real-like scenarios. There are some imagers already in the sub-$1000 range on Aliexpress (beware, Chinese often do not make differences between near and far IR and may be confused with their own merchandise, many just hustle goods they don't understand (fine with me but you have to count with it)), and then there's the eBay, though its disadvantage vs the Chinese is that they typically don't sell this outside of the US, and smuggling step is needed which adds a bit of risk and a lot of logistical overhead. (Yes, not all hackers/makers are in the US, and some are getting increasingly pissed at the US attempts, luckily increasingly ineffective (thank you, China!), to control the technology proliferation. Dual-use my rectum, access to multispectral imaging tech should be a worldwide inalienable human right.)
A bit more adventurous approach, for which I sadly lack resources (and worldwide the hackerspaces so far tend to be underequipped with vacuum tech, and sol-gel thin films aren't too well mastered in the semiamateur domain yet too), is attempting to deposit a patterned thin film of a ferroelectric material on a suitable (aerogel?) substrate, on a matrix of readout electrodes. An opensource homemade-able FLIR array would be a cool project.
If we want to deny the adversary the visibility in a spectral range, we have to be able to see in that spectral range ourselves, to have the proper feedback for what we are attempting. That applies to visual camo (easy with standard-issue Mk.1 eyeballs), thermal, and even for longer wavelengths like radar cross-section issues and TEMPEST shielding.