I was thinking that electrohack-usage ought to run off Electronics, rather than Computer, but then my concept of the electrohack is some sort of cross between John Connor’s ATM-defeating device in Terminator 2 & Hudson’s rig in Aliens.
Regarding the issue of recipes appearing at levelup: Bear in mind that unless the devs deleted them already, there are Electronics books going up to skill 10, and at least the first two (skill 5-6 IIRC) can be found in most libraries. My character has the complete set, and is around Electronics 8 pretty much from book study–with CBM installs & making an electrohack, before I found that it’s not really worth using on bunkers accounting for about a point. The high-level book’s description specifically states that it includes step-by-step guides &, IIRC, illustrations. If you’re grinding Electronics, it’s because for some reason you don’t have access to the existing literature.
Motion trackers with audible alarm and/or visual display* should be craftable. The Nostromo’s engineering department (see: Alien) whipped up two of them at the same time as they made electric prods for chestburster-hunting. Figure no more than Electronics 5 for either; Mechanics as a secondary.
*Cyan question mark ? at exact location, provided that the player’s wielding the thing. Otherwise, tick with noise 2 if on person, and whatever noise is needed to wake sleepers if left on but not in inventory.
Hearing-enhancer ought to be craftable too: if one can make a pre-loaded mp3 player from parts, simply making a sensitive microphone with filters and hooking it up to earbuds shouldn’t be a challenge. Would guess Electronics 4.
Not sure how hand-held sonar would work–guessing some sort of metal-detector* thingum? Probably shorter-ranged than the bionic but it might be worth carrying in questionable areas, especially at night.
*Incidentally, this would be another way to find land-mines, etc–both the sonar and just a plain ol’ metal-detector. MD is probably worth adding.
Re bionics: the player already earns them through finding & install, especially since the devs nerfed the sets down to individual bionics. (Seriously, what was the reasoning there? The good stuff is/was already nontrivial to find–I’d had one Lab finale come up Bionics…and completely empty.) I don’t want to hear somebody claim that they’re “too pro” to use them personally, but it’s OK to make them even worse.