Cups is so much better then everything printer related that is available for Windows and it works so good that even Apple was not able or willing to create something on their own and are using it their OS on all devices. Yes, the web interface is dated but nearly every Desktop comes with a modern integrated interface for printer setup and configuration. It is ages that I had to use the web interface. Cups comes with a boatload of printer drivers out of the box. And if not then there are often PPD files on the homepage of the printer manufacturer.
Multifunction printers are a special case and if they are supported or not depends either on how the device is build (are the parts addressable Independently as printer, scanner, modem/Fax) or is it all a integrated mashup that needs special software or drivers from the manufacturer. In the first case can the printer part often be used with cups and the scanner with sane. Well in the second case there is not much that Linux developers can do without support and goodwill from the manufacturer.
Internal HDMI capture cards are barely supported, there are some professional brands like blackmagic that have support but nearly all consumer grade capture cards are not supported at all, because the companies who make them don’t care about Linux.
USB based capture cards often work because they use the same standard protocols as USB cameras.