"I'm not sure either...." <- disclaimer: i am not a lawyer 😉 i've seen a lot of desktop applications include the licenses somewhere in their "about". check e.g. your current browser (i use firefox, under "about" i get a link to "about:licenses" which in turn lists all licenses used by the various libraries which it uses). i've also seen a lot of enterprise software ship the software package with an SBOM (software bill of material) or have the SBOM as a separate download. the SBOM is generated by some tool (i think i recently read that GitHub Dependabot can now also do that?) which lists all 3rd party dependencies and their versions and licenses. in the "enterprise IT" environment it's usually just compliance BS: nobody will do anything with it except tick a checkbox that it's been done. these are companies paying a ton of money for some software (and 24/7 support with quick resolution times) and often have an escrow rule in the contracts as well (i.e. if the manufacturer folds then the customers get access to the source code through a 3rd party (i guess a lawyer?) which acts as escrow and has a copy of the code). the compliance BS aspect however does not take away from the fact that i strongly believe in open source and think that a lot more should be open source and that companies of course need to fulfill FOSS licenses! i would presume that for embedded systems you can go down a similar route and host the SBOM on your website (e.g. on the same site as your release notes & firmware updates (if you offer such things)) and add a reference to that in your user manual?