I generally agree with
svgurus.
The earlier Seek cameras weren't terribly good but the more recent ones are much better. There are people here who can advise on specific models better than I can.
Broadly speaking, almost any laser-grade zinc selenide (ZnSe) lens will work well-enough as a macro lens for any of these cameras and enable you to see closer-up, much in the same way you use a hand-held magnifying glass.
Here are a couple of quickly-made images of a Raspberry Pi taken with a Seek (Reveal Pro FF) 320x240 camera without and with a hand-held ZnSe lens. The camera is in the same place for both images. I didn't make any attempt to get maximum magnification, just something to show the difference.
Without the lens the Pi is just a blur. With the lens you can clearly see individual components. The actual field of view you get will depend on the focal length of the camera
and the auxiliary lens; it's best to get a camera with adjustable focus if you can (several Seek dongles do this), because you'll be able to get much better-magnified lenses.
Don't worry too much about resolution, other than to suggest that 160x120 would be a practical minimum for use on PCBs. More pixels mean you can get a wider field of view
or a more-detailed view of the same area, but in practice any camera will let you home-in on whatever part of a board is getting overly hot; you can then use the close-up lens to see what's going on at component level.
For this sort of application - looking at hot things - you won't need to worry about the camera sensitivity (usually expressed as 'NETD').
Any uncooled LWIR camera will easily see temperature differences of 1°C - and any component that is only 1°C above its neighbours is more than likely what we call in the trade "working OK"...