This is simply normal distribution of software that includes GPL components. The fact that the binary is embodied in a physical device only allows a few extra source-distribution options (namely 6(a) and 6(b) in GPLv3) including the written-offer-for-source option even for commercial distribution. (Normally written offers are allowed only for noncommercial distribution.)
Any part of your software that is part of the same work, under copyright law, as a GPL-licensed component has copyleft requirements applied to it, and you must distribute the complete source code for the work any time you distribute the binary. This is the normal operation of the GPL's copyleft provisions; it is no different for your case.
In contrast to the GPL, LGPL components limit their copyleft obligations to modifications to the library itself. Software that makes use of LGPL components as a library do not have copyleft requirements applied to them, even if they create a single work with the library under copyright law.
As a general rule, using a GPL library requires you to disclose the source code of your whole work, while using an LGPL library only requires you to disclose the changes you made within that library.