I don't know what 26650 batteries are safe for different builds, would maybe peek around the Battery Junkies subforum for a look, but I never recommend going below 0.2 on much of anything mechanical...as a rule of thumb, "legit" batteries are made by Panasonic (though not many of them are good for vaping), Samsung, LG, and Sony - everything else is a "re-wrap" where companies buy "seconds," or batteries one of the manufacturers thought wasn't good enough to put their own logo on, and they usually exaggerate the specs, crossing their fingers no one blows themselves up (people inevitably do, but it's somewhat rare).
I have a couple old eFests dating back to before I learned all this, I run them in regulated mods or flashlights but won't let them touch my mechs.