But maybe you'd find it better to directly try to compile an u8glib "Hello World" example, which is likely to throw the same exact errors. The reason I am reporting this is that several sketches are ...

I made a board with 328PB and burned the MiniCore on it. The IDE does not support compiling code for U8Glib with MiniCore when I use 328PB, but it works fine if I switch to 328P.