There are also shops in China that will upgrade the SSD in a mac mini for cheaper and they will do all the work of the DFU restore etc.
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With direct physical access, a lot of things can be done which cannot be done remotely, e.g. attempting to boot from an external device, possibly using hardware fault injections to bypass protections against that, attempting to read data that has not completely decayed from the DRAM modules, replacing some hardware component or inserting an extra component that would enable spying in the future, making copies of an encrypted SSD/HDD with the hope that after making other copies of it in the future that will enable breaking the encryption , if that is done using an encryption mode that does not protect against this kind of attack, and so on.