I understand how toggle bolts work, lathe and plaster is also generally significantly stronger than drywall. All I’m saying is this wall is suspiciously thin and op can’t even find framing in it. I’ve seen “walls” where the top and bottom plates were fit with friction. Like I said, it’s probably fine but I certainly have questions.

Its not what the anchor can hold, it’s about all the assumptions everyone is making about the construction of the wall itself. OP says it’s 3” thick and has potentially 2 layers of drywall on one side. OP also hasn’t been able to definitively identify framing/structure or anything really. It will probably be fine but no one here has enough info to say for sure. There is lots of janky shit out there in the world of older construction and DIY.

You cannot safely mount something as heavy as a pot rack to a wall of unknown construction. If it’s really only 3” thick it’s certainly non standard construction, by todays standards at least. The only time I’ve seen walls that thin (~2”) they were plaster with steel angle in the middle. Essentially just enough structure to support the plaster and that’s it. The safe thing is to not mount it to that wall unless you can learn more. The other option is an expansion anchor and pray.