Yes, I experimented with this too -- and got it to work. But strangely, if you leave out the

# eval: (org-babel-lob-ingest "./a.org")

# eval: (org-babel-lob-ingest "./b.org")

lines and do a regular `org-babel-lob-ingest` (or C-c C-v i) on those two files -- it doesn't work. Rather bizarre behavior, IMHO.

Anyway, the dream behavior for LOB would be to simply add your files to your `org-babel-lob-files` in your Emacs init, start up an org file -- and be able to simply use all the LOB files in your "live" `org-babel-library-of-babel` list library.