The Division Flute / Violin
Two publications in which popular grounds of the time are published with fun written-out improvisation like melodies. The publications use many of the same grounds, but each with slight melodic differences. There are however also some grounds which appear in one and not in the other.
These can suggest ways in which we could improvise on these grounds nowadays. Because there are so many it really gives a sense of the style and possibilities.
Each collection also includes some solo music.
https://imslp.simssa.ca/files/imglnks/usimg/8/88/IMSLP97963-PMLP198850-firstpartofdivis00rugg.pdf (1685/ 1688/ this is the 6th edition from 1705)