I don't recommend it but I had an ird "mechanical" dropper.(which looks similar to the tmars ebay dropper) Got on the cheap to see if I really even wanted a dropper. It has slop, is finiky to operate and horrifying to ride but is cheap! But honestly not cheap enough. I would compare it more to a sketchy hite rite.
I also had a hite rite on a gravel type bike and that was great, it's not the same as a dropper but you gont have to get off your bike to lift yr seat.