how do I roll back to Sonoma from Sequoia?

Backup, make a bootable Sonoma USB installer and boot to it, reformat, install, restore.

Create a bootable installer for macOS - Apple Support

Notice that some libraries like Photos do not work in Sonoma anymore if a later macOS like Sequoia has touched them.

Did this computer original ship, as new, with macOS 15.x Sequoia ?

Of so, not possible to downgrade to anything older than what it shipped with

macOS Sequoia likely blocked your printer, film scanner, and audio transfer kit due to updated security and driver compatibility changes. Apple’s newer macOS versions often tighten system permissions and phase out support for legacy or 32-bit drivers, which many older devices rely on. To resolve this, check the manufacturers’ websites for updated drivers or software that’s compatible with Sequoia.

You might also need to grant permissions manually in System Settings > Privacy & Security > Full Disk Access or Input Monitoring, depending on the device. If no updates are available, using a virtual machine or rolling back to an earlier macOS version could be a workaround, but it’s best to check with the device makers first.