There seem to be two sorts of pipefish in the FW trade: Doryichthys species and Microphis species. The Doryichthys are true freshwater pipefish; the Microphis tend to be brackish. If this were me, and I wasn't sure which I had, I'd be tempted to maintain them at SG 1.002-1.003 until I was able to visit Fishbase and pin down the precise species. Slightly brackish water shouldn't harm freshwater species. This is a good approach with gobies, and should work with pipefish too.
As for "easy", well, no. None of the pipefish is easy to keep. All require constant supplies of live foods. Unless you can see them taking frozen foods in the retailer's tanks, assume they must have daily offerings of daphnia, brine shrimp, etc. and act accordingly.
Needless to say, they're species for single-species tanks, and most are gregarious. Shady, planted tanks with gentle water current (ideally, air-powered) works best.
Cheers, Neale