The products are made in the Ruhr area so it shouldn't be difficult to find.
At least here Forte is a premium brand mostly sold through garages. Aka the garage sells you a forte treatment and gets to charge for the product as well as labor. Liqui Moly is more towards the consumer.
That said, Liqui Moly does have a "Pro line" as well, stuff that requires more than just dumping it in the engine or fuel tank. I have a feeling that their pro line engine flush product might destroy the lubrication properties of the engine oil, which isn't an issue if you use it as described (IIRC pour it in and idle for an amount of time before performing an oil change) but you're probably going to have a bad time if you don't read the instructions, pour it in the engine on the parts store parking lot and go.
Rur, different Ruhr. I didn’t know the difference either, @DanRoM explained that one to me.
Because I don’t have a garage to work on things, I wouldn’t get something that goes into the oil. I’d try pouring something into the fuel and hope for the best.