A reasonably proficient caster who knows how to do a double-haul to build up line speed and understands the concept of what "loading" a rod tip means, can pretty much get a fly out into steelhead holding water with ANY fly rod, whether it's a $ 50 Fenwick beater or a $ 1,000 Sage boasting proprietary resins and high modulus aerospace-grade carbon fibers.
It helps to have a good quality fly line with a slick coating and the grains laid out in the proper place to get that fly out into the river, though, and if you're lucky enough to hook-up, it's nice to have a half decent fly reel to fight the fish on---I mentioned rim-control because no matter how good or bad your drag system is, an exposed rim that you can "feather" with your palm is a very efficient way to slow down a fish.
The rod--- if I was going to buy just ONE rod to cover both steelhead and salmon as you mentioned, I'd go for a 8/9 or a 9/10 rather then the 7/8 you brought up
I have broken two fly rods on fish---both were trout rods or light steelhead rods (6/7) that I used on salmon because I was too lazy to go get a proper (heavier) weight rod.
An 8/9 will give you way more flexibility if you want one rod to cover several different bases---Or you can go drink the typical fly-fisherman Kool aid that I ended up drinking--- buy a different rod for every possible fly fishing scenario until your entire house is filled with rods...
good luck, and don't think you need a specialized rod, "spey" rod, or any piece of equipment that costs a pile of money to fly fish for steel.
The young turks these days all think they need the latest and greatest technology to chase these fish. You absolutely do not, and you can save yourself lots of money by picking up the equipment they discard in their endless search for the "ultimate" next best thing...