To address your OP, the SM_G930W8 is shown as a supported device at the foot of the page here https://doc.e.foundation/devices/herolte; it was originally proposed as supported by Easy Installer here [LIST] Devices working with the Easy Installer - #7 by aibd; but it was never validated and no longer appears as supported by Easy Installer here https://doc.e.foundation/easy-installer.
I can’t seem to get the S7 into the bootloader …
I imagine that you can actually reach Download mode or Odin mode? – would you care to send a photo of your Download mode or Odin mode screen which will often give a clue if there still exists some manufacturer lock within the device.
Samsung recovery seems to have a failed download
Please do not expect the Samsung recovery to help you !