For a BTC related project I need to create some addresses on automatic mode; the machine is offline, the machine prints both WiF Key and matching Address, there's minimal interaction for this, so it won't be able to pick much from its own memory in order to generate a good Random seed.
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Do you think this solution would provide a good enough Random generator? If not, what/how do you think this can be improved?
Good enough? No. You need additional entropy sources. Use the Hardware RNG included in ESP32. Add a microphone. Add a camera. Add some buttons to be pressed. Feed all the data together with timestamps into Fortuna CSPRNG. Also a second seems too short - feed it for a minute.
If this is too much just using the Hardware RNG might be better than radio module.
Will you be around the device every time it's used?
Are you sure the printer always prints what is given?
Does the printer remember the last page(s) it printed?
Is there an "echo" from previous printed pages on the current one?
ESP32 has wifi. Maybe it has a backdoor. Can you make sure no radio wave reaches the module?