I'd try the Google Pixel Tablet - $399
- First-party Android support
- Not horribly expensive (although not cheap)
- Included stand with charging/speaker (nice for a static office environment) that leaves the USB-C port free, so no additional dongles would be required for the NFC card reader
So as you've discovered, USB host mode support for Android devices can be hit or miss. Worse still, there's almost a total lack of any sort of comprehensive list as to which tablets actually support USB host mode. So far, the most reliable complete I've been able to find is actually the Square Device Compatibility site and Devices with Known Issues list; the Square Reader (1st generation) is a USB NFC reader and thus relies on the same feature set that you're looking for.
While it is possible to enable USB host API support on basically any device by adding the appropriate XML file to the right directory, this can require rooting on certain devices and is a bit of a pain—especially for larger deployments.
While I haven't been able to confirm that the Google Pixel Tablet specifically supports USB host mode, it appears that all Google Pixel phones support USB host mode. Thus, I'd assume that the Pixel Tablet also does.
For security reasons, many Android flavors disable this functionality by default—including the versions that have shipped with most Pixel devices. You may need to enable USB host mode in the settings; here are some instructions for common device brands:
- Samsung Galaxy Devices: Go to "Settings" > "Connections" > "USB Accessories" and enable "USB OTG."
- Huawei Devices: Go to "Settings" > "Advanced settings" > "OTG connection" and enable it.
- Google Pixel Devices: Go to "Settings" > "Connected devices" > "USB Accessories" and enable "Use USB Accessories."