Yes and no. the materials aren't the same so you can't replace steel with plastic 1:1. The plastic guns don't always look nearly as sleek as steel or aluminum ones. pistols don't look much different because the plastic frame isn't containing most of the energy, the metal slide and barrel are.
I definitely see how it could expedite things on the consumer end, if you had a part on one of those guns you COULD go and just replace those parts with pla but if you have parts to functional spec you can very easily send the measurements in to a CNC shop that could cut and grind your parts for you and send it back for you to put in your newly reliable revolver.
Just like anything else, there is a wide gamut of price points.
A good starter printer like a ender 3 V2 iss only Abt 250$ shipped (175$ used) and good pla pro that can take the heat and pressure you need is only Abt 35-40$ a roll, you can get Abt 4-6 full frame handgun frames printed from a roll if you have none of them fail. Their really isn't much more to it than that, from there you just need a parts kit, complete slide/upper, lower parts kit, and rails, for a Glock this is normally around <300$ when all is said and done, mine costs me 288$ all together. I have some good links here:
