Since you're in Spain (well, Catalonia…), you might consider an Oribike, either C8 or M10, whose only retailer in Europe is in the Murcia area (Cartagena, of all places.)
It folds pretty much like the Brompton, is cheaper, and lighter. I bought a second-one recently, and was pleasantly surprised.
The only drawback is that its stem prevents a frame-mounted bag à la Brompton: It only takes a small stem-mounted bag, and/or a trunk bag on the rear rack.
For just a little bit of money, I would ask the company to replace the transmission for either a Nexus/Alfine 8 or 11 speeds. Those bikes used to be available with a Nexus 8, but for some reason, Oribikes only sells them with derailleurs nowadays.
https://www.pivotpro.es/es/39-ori-bikes