Paperless-ngx + ScanSnap iX1600. Works with a samba share that is very easy to set up in Linux these days. Fast, easy, and you can have different scan profiles to set the destination folder. Push a button for the type and a button to scan. Paperless-ngx automatically files and tags reliably. It is saving me hours per week in filing. Can't recommend it enough. This is a personal system -- not sure how it would scale to 100k - 1M+.
I've had an iX500 for a few years. You're right, and it's also a complete tank. I deployed several of them to a doctor's office that had to scan lots of paperwork every day, and they all worked perfectly all the time, every time.
Fast, stack of pages, but also compatibility with different destination types, ease of setup, and no cloud account required (looking at you Raven) and your PC doesn't have to be on for network scans (direct, not passthrough).
But yes, the scanner is pricey. It was definitely an investment.
I’ve got an ix500 and I’m suffering for no SMB support.
The only thing that comes to mind is either do a convoluted SnapScan Online -> Google Drive -> rclone -> Paperless or bite the bullet and figure out how to directly scan into the local box via USB.