Just as I feared, there is no driver. This is what I received from Waveshare:
Hi dear,
I saw your message left:
Will the 800x600, 6 inch E-Ink display HAT for Raspberry Pi or the 9.7 inch one work as a monitor once the bcm2835 library files are installed? I wan’t an e-ink monitor to replace an LCD monitor.
The 6inch and 9.7inch epaper can not work as a monitor since there is no driver support.
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Best regards
Waveshare Sales Team