A man after my own heart, but this is a massive subject and a bit difficult to know where to start.
Much of Thalberg has yet to be recorded, but you will need to have a pretty top notch mechanism for some of it. Some solo works by Herz, Henselt, Kalkbrenner, Pixis, Leybach etc..... are worth looking at.
If you have not done so, it is worth trawling through John Kerseys site
https://henseltlibrary.org/ . He has recorded many completely forgotten pieces and has a reasonable amont of pdf's.
For complete obscurity, check out my Hay on Wye Pilgramage thread on pianophilia.
However, to reach some jewels you have to search through a bit of mud, but it can be fun.
Thal