It is feasible but not purely with software, the SSD chip has to be desoldered from the circuit board, the socket inserted in the board and then the copying can be done as many times as needed and the combinations tried. There are companies that do exactly such kind of intervention.
Not on the 5, apparently. My understanding is that it isn't the SSD but rather the flash on which the encryption key derived from user input is stored (the part you unlock with code and is wiped after 10 tries).
I don't agree. There were more texts claiming it can be done, they just have to try the combinations on the same circuit board, because one of the parts of the key is the part of the hardware, but the copying of encrypted data and then restoring from such backup can be done outside of the board, nothing is against that. Here's how Chinese trivially remove and replace the "solid state disk" chip.
Yes it's just a chip that has to be copied, it's not a disk as we understand it in notebooks in a sense "a bunch of chips connected via SATA or M2" it's lower level but the principle is the same.
https://www.aclu.org/blog/free-future/one-fbis-major-claims-...