Removing the crank arm (square taper) on a Chinese (PooBoo D 577) stationary bicycle
It sounds to me as though the crank arm may well be threaded to the old french standard of 23mm as used on old Stronglight and TA chainsets, rather than the standard 22mm which is used by Shimano, Campagnolo, etc.
There are still crank pullers available for 23mm chainsets, I have one from VAR, since I have a couple of old TA Cyclotouriste chainsets on a couple of old bikes. The VAR puller is available from this location.
(I make no recommendation, as I have not used this supplier, other suppliers are available, Your experience may vary, etc...)