So I've got the hots for a thermal sight of some sort.  Lots to choose from a specs to familiarize with.
Not sure of budget just yet, maybe $2-3K
Do units exist that clip on the front of an optic like a 1-6X Primary Arms ACSS or similar?
This is one route that seemed like an option, vs a dedicated unit that would require taking off the day optic with a mount that returns to *near* zero.

For the price range you're in you're better off with a dedicated scope.

Theres a clipon near your budget. Bering optics hogster-C i believe.

I have never used that but ive used a flir t50.

Good thermal clip ons are outrageously expensive. A $3000 dedicated scope can be very decent. Check Pulsar scopes in your range.

FPNI. Get a dedicated thermal scope.

Ok, that Bering unit looks very interesting and just what I was looking for.  Been watching a few reviews.  Seems like just the ticket.
thanks all

The Bering Optics Hogster-C available at Night Goggles is a nice clip on. You buy an adapter for each scope you wish to use it on. It can save up to 4 different gun profiles. However, you are adding weight and bulk to your weapon. The Bering Optics Hogster-R is the weapon's version. It is a $1K to 1.3K less expensive option depending on if you want the 25mm or 35mm option. The -R versions come with a QD mount, so they can easily be moved from gun to gun, and also store 4 rifle profiles. If you want to use a glass scope, and quickly move to a thermal without having 2 scopes with QD mounts, a clip-on makes sense.

Both the weapon's sight and the clip-on can be used as a scanner. However, the clip-on's base mag is 3x, and the 25mm is 1.4x and the 35mm is 2x. It really comes down to field of view and base magnification desired for the scanner portion.