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I dunno. If I'm spending $1000 or more in a camera, I see no reason to cheap out on the last few dollars for an aftermarket battery. Sometimes they work out but we've all heard stories about third-party battery packs swelling inside the camera, etc. Besides, Fuji's OEM batteries are far from the most expensive compared to some other brands.
As long as you don't care about the inaccurate battery percentage display (and the camera suddenly switching off at 10%, 17%, 14%, 8% or whatever misleading value), third-party batteries do work with the new models. Of course, they don't offer the improved heat dispersion of the 126S type which is useful in the X-T2 under certain conditions.
That said, don't leave third-party in bodies that you intend not to use for weeks or months. The missing deep-discharge protection bears a risk of the battery swelling like a balloon in the camera, so it may become quite difficult to get it out. This also happend to my dad a few months ago.