Back when I worked at palce that made electromechanical airbag sensors. After soldering, the electricals got a conformal coating over it. Then in the 'can' they were filled with a two part epoxy. Had some flexibility even fully cured.
The Chrysler ECMs seem a little different - at least from the photos I saw. Looked like like top seal poured over a different material inside.
???
If Jim has cut one open be interesting to hear what he found. Nacho is smart but his spanglish can be brutal. lol.