Yes, that's one of the advantages of owning a .357 Magnum, you can shoot anything from very light .38 Special "mid-range" target loads, to the heavy "blow the barn door down" hunting Magnum loads.
The only thing to keep an eye on, is after shooting .38 Specials in a Magnum, you need to do a GOOD job of cleaning the cylinder out. .38 Specials will allow fouling to build up in front of the shorter cases, and Magnum cartridges may refuse to chamber.
Just clean throughly, and you will have no problem.
Some people use Auto paste wax, but some people report the wax makes blued guns look blotchy when they get hot from firing.
I'd recommend wiping it down with a new, clean silicone cloth. When the cloth gets dirty looking, it's usually full of grit, pitch it and buy a new one.
Nickel is tougher than bluing, but it's not as durable as you might think. It can crack, chip, and peel. Some nickel guns flake around the muzzle and the front of the cylinder from firing.
When cleaning the gun, you can use standard gun bore solvents, but don't let them soak for long periods of time. Most gun solvents can damage the nickel plating if allowed to work on the finish.
To prevent this, just clean your gun the normal way, wipe all solvent off, and rub down with the silicone cloth.
I don't recommend any type of polish or cleaning chemical to be used on the plating, to "shine it up" Some people will recommend using Flitz or Brasso or other products to make it shine, but I don't think this is a good idea.
Other people have heard that bore solvents can damage the nickel, so they will tell you not to use standard bore cleaners. Again, they only do damage if left on the finish for long periods. You run a bigger risk NOT properly cleaning the gun, than any possible damage to the nickel.
Also, I recommend staying away from "non-traditional" cleaning tools, chemicals, or methods. People will tell you to use all kinds of stuff, because it's cheaper or "I swear it works better".
These people aren't going to offer to pay for a new gun if their stuff damages your gun. Saving a dollar while risking a Python is "Penny wise, Dollar foolish". Stay away from them.
To maintain your Python, get a GOOD stainless or coated cleaning rod from Brownell's Gunsmith Supply. Use only synthetic or brass brushes, never use steel brushes. Use a good bore solvent, with cotton patches.
If you're going to shoot lead bullets, buy a Lewis Lead Remover Kit. This is a special tool used to remove lead from the bore and chambers WITHOUT damaging them. The Lewis tool has been around for MANY years, and is totally proven to do the job without damaging an expensive gun.
Again, people who tell you to use steel wool, abrasives, or super market products aren't going to say "Sorry, I was wrong, here's $1000.00, buy yourself a new gun".