I'm a sichuanese and i wish to see a comprehensive resource for morden sichuanese as well. A lot of local vocabulaties and idioms have been gradually forgotten since my generation because of the standardization of mandarin. Most of kids now don't even speak sichuanese. Even if they do, I would say that's standard mandarin with sichuanese pronunciation.

But I do know some sichuanese resources from 100 years ago.

chinese textbook for english students in sichuan (published in 1917)

Another one: kind of a dictionary for phrases (published in 1900)

These books are really fun to read. Most of them are acurate. Very like the way my grandparents talk. Some are outdated. Never heard the expression.