The first/last images look like a Belgian 7mm pinfire. The proof marks would provide more information. I like the bone grips on it.
The 2nd and 3rd images look like Belgian made caplock pistols with screw barrel loading. They have German commercial proofs and might have been made in Germany or imported from Belgium and proofed in Germany?. Anyway, they would be no older than 1891 the year the Germans started to use commercial proofs.
The little revolver with the wood grips looks Belgian or maybe German w/Belgian parts?. Can't say for sure but most of these were chambered for the .320 (.32 Short Colt) cartridge. It could be a .22 but I can't see it well enough.
The single shot with the plastic grip is interesting. I don't know what it is, maybe a small signal pistol?