I'm in a similar boat. I wish it were possible to externally verify in some way. I'm a bit skeptical of how easily a lot of newcomers to meditation claim to have reached them.
Although I agree that a lot of people may be overblowing their experience, either by mistake, through ignorance, or else for clout/internet points, think about it this way: when the Buddha was alive, the jhanas were standard practice, and had been for as long as yogis could remember. The Buddhist teaching almost assumes a familiarity with the jhanas and doesn't really explicitly teach how to access them. The entire teaching is based on the Buddha learning the jhanas from various teachers of the time, mastering them, and eventually finding them unsatisfactory. Yogis who came to the Buddha seemed to already have an understanding and background with jhanas, which the Buddha then taught them to use to realise what he himself had realised. What this tells us is that jhanas aren't some kind of lofty, difficult to achieve thing that only a select few ever achieve; instead, it seems to suggest that it's something that's available to anyone with enough dedication and is something that transcends traditions or religions, and has been known about for millenia.