To craft the new electronic elements you’ll need to find and extract a new mineral:
It’s called germanium and was used to make transistors in the early days of electronics. It will have abundance similar to that of malachite (copper ore).
I finished doing the new Recipaedia. There are at least two more things I need to put in 1.19 before release: the new help system (ugh), and an improved save system. My list for 1.19 also contains about a dozen of lower priority things, but they are not critical.