Does the resin vary from a printer to another?
According to Formlabs (at least their FormLabs Form 2 and 3 models), their resin is 405 nm which is a fairly standard resin.
There's a wide variety of resins our there that are compatible with 405 nm, and many resin makers/resellers advertise what brand, make, and model of printer they are compatible with. I have an AnyCubic Photon v1 and it uses the same 405 nm resins. You might have to do some testing to see what specific brand or style works for you, including changing your settings (if possible in the software you use). FYI, I use a version of CHITUBOX which does allow settings for exposure time, raise height, pause time, and a few others.
Knowing that it uses 405 nm UV also allows you to know what kind of UV lights to get for easy indoor curing, too.
I'd like to say that it's not likely for these resins to damage the printer, but FormLabs seems to use a plastic tray, instead of the aluminum tray I'm used to so I don't know if there would be a chemical reaction, though I'm skeptical if there would be. I'm assuming it's using a similar FEP clear film for the bottom to the AnyCubic, but I can't confirm this, since the FormLabs film seems to be integral to the tray, rather than replaceable.
I can see why you are looking for other resin options. One place I saw online has a 1 L FormLabs cartridge for \$150, when 500 mL on Amazon is usually between \$20-30. I've seen special resin, such as flexible, as high as \$60 for 500 mL and ABS-like resin for $40, though. Water washable resins seem to be in the \$40-50 range. There's also &quot;natural&quot; or plant based resin for about the same price as regular resin, but might have a different reaction to your tank.
I'd assume that every brand of resin (except for the rebranded stuff) has their own chemical makeup besides the various types of resin, so you might have to some testing, although I realize that messing up a tank that's \$150 to replace is not exactly something you want to do every day.
I can tell you that I've used at least 6 different brands of resin and they all react differently to the UV. I mostly have tested clear, and just that produces a variety of results, from how easy/hard it is to cure to what color it turns when it over cures. (I'm still trying to find a clear that fully cures actually clear.) Where I was going with this is that with all these resins I've used, I haven't had any that caused damage to the FEP film. Some have stuck really hard and I had to be really careful pulling it off. However, I've only had 1 film need to be replaced due to clouding, and I have 4 Photons and used all resins I've tested with all my machines.