These numbers really depend on the compressibility of the content, compression scheme and the type of batching used. The metadata overhead is fairly minimal. LogDevice allows you to configure this on either the client, sequencer or rocksdb level.
I recently came across the following custom Eachine E010S build [0] based on a Beecore F3, which can be programmed with e.g. Betaflight, although the video processing would have to happen on the receiver side...
Almost every program nowadays is compiled with W^X (--no_execstack) by default which means the memory is not executable and writable at once (Windows equivalent is DEP). Still a good example of how a basic overflow can lead to arbitrary code execution. A follow-up post using ROP or return-to-libc would be interesting, with W^X enabled.
[1] https://logdevice.io/docs/Settings.html#security