There are several brands out there. Fluid film is a good product. Wool wax is another product I have heard about that I think is similar. If you want someone else to do it, see if you can find Krown. It is a Canadian product and is linseed oil based. I had it applied to all of my vehicles before I started doing the rust preventative myself. Krown is a good product, initial cost I think was $250-300 and then yearly top up applications are around $60-70.
If you do the rust prevent yourself, pick one of the products and stick with it. Amazon sells Fluid Film in spray paint cans, also are cans for professional paint spraying equipment. You might even be able to find a gallon can (or bigger) and with a brush, “paint” the FF on. It takes me about 30-40 mins to apply it. It will drip somewhat so wear your wrenching clothing for sure. Eye pro is a must and I would apply in a well ventilated area only or use a paint respirator. I dont think its necessesarily toxic but I wouldnt want to breath in Fluid Film for an extended time. After application, a drive along a nice dusty road will allow dust to adhere to the Fluid Film which IMO is best.
I apply FF when it is warm outside as it allows for better adhesion to the metal. Once or twice a year. Also, FF will not remove rust that is already there. It will only prevent more rust by keeping the metal surface lubed. For rust removal, depending on how bad it is, you would have to use some sort of acid bath or specific product. Not sure if a rust removal product and Fluid Film would be compatible. Research is critical. I have had great results with FF and it is worth the cost and effort IMO.