To examine in radare2 you can think as 'print values' and you can use:
px show hexdump
pxl display N lines (rows) of hexdump
pxr[j] show words with references to flags and code (q=quiet)
> px [nBytes] @[address][offset]
"Print hex 10 bytes at rbp plus 10"
[0x5618eccbf77a]> px 10 @rbp+10
J5 looks like a UART connector and the JT_ pins are likely JTAG. UART should give you console access to manufacturing/diagnostic commands, and JTAG should allow you to the debug the code (firmware) running on the controller CPU.
As for J3, at a guess, ROM/FW allows you to switch from the firmware stored in the flash to the built-in CPU boot ROM (e.g. in ...
Actually, I think this should technically be possible, without having put too much thought into it. Freeze all threads, save thread context state for all of them, enumerate all of the memory used by the program and dump it alongside meta data.
A problem would be stuff like open handles (files, connected sockets etc.) but for programs within a limited scope ...