>>10353446As a fellow Technic enjoyer, I'd actually kind of recommend you buy separate parts. You don't usually get very many pneumatic parts in most sets, and the ones that do deliver many are either vintage (such as the 8455) or fancy (such as the Mercedes-Benz Arocs). You can usually find sellers that have a bunch of cylinders in stock for pretty cheap on Bricklink.
Battery boxes are basically free for all generations, and you can sometimes get okay deals on motors through cheap, small car sets. It kind of depends on which generation of electrics you want to go with as well. Power Functions are generally regarded as a bit more universal and simple to use than Powered Up. Old 9V parts are great but they're getting old and unreliable.
If you want to build Technic sets, I STRONGLY recommend older ones. Having just put together both the 2005 8421 and the 2021 42128 in the picture, the 8421 was just a lot more challenging and fun. In general, the older the set, the more challenging the build. Mid-to-late 90's sets are generally considered the best ones. They're brick built like normal LEGO, which is just more pleasant to deal with in general.