My $.02...
The assumption: you're an active-duty MAF or CAF pilot early in your career
The background:
In my experience, "Normal" career progression to O4/O5 is ops tour x 2 and a ALFA/ALO/Trainer/schoolhouse/FTU/OSA/WIC/TPS then ops or staff/school then ops or staff or command, etc. The order varies a little, but if you're within your first three assignments, applying to the U2 instead of schoolhouse or OSA or WIC or ALFA should not been seen as a bad thing. If you're "due" for your next ops tour, or the "dessert" tour (OSA/schoolhouse/FTU, etc) you could apply without raising too many eyebrows. It's selective-hire (meaning you have to make the cut to go) and Sq/CCs understand that, so most see going to the U2 as a good thing for YOU and the U2 program. They should also tell you the career impacting pros/cons of going to the U2 and of staying "mainstream."
You should not worry about "seeking information" about alternatives to mainstream careers. There are a LOT of cool flying jobs in the AF, and people get them by asking about them. Here are some non-mainstream examples: OSA, Test Pilot School, Big Safari, DCMA, AFFSA, green/blue door, exchange, DIA, FAA flight inspection, anything in AFMC's Test/Eval/Acquisition sections (usually after TPS or in ASC/ESC). MAJCOM staffs often have test/acquisition positions to run and fly new things the MAJCOMs are working on (C-130 AMP, uh, maybe scratch that one... KC-46, F-35, NextGen Bomber, you get the idea).
The technique:
If your Sq/CC or DO doesn't have the info, or presents a one-sided view of anything, then seek info from others (like here, or in other units in your airframe on deployments, or call the units you're interested in. You can also call/email your specific handler at AFPC: he or she will get notified of upcoming openings in these special units and may let you know about them. Search for "11x" (F/B/M/R, etc) authorizations on AMS website--it'll tell you the locations/units/rank of UMD positions you might find interesting. Search the AF Portal for announcements.
Finally, be a bro, because sometimes the units flying these missions call to recruit YOU, and that's the ONLY way they hire. Some are classified, some aren't, some you stay in (once you're in, STS) some are one-tour only and back to your MWS.
Good luck!
ETA: YMMV