I've been using Linux for almost 25 years and I've never once considered mouse or keyboard incompatibility, and that's including ADB, PS/2 and DB9 devices, let alone USB.
As far as I know, you can intercept any signal from any such HID device and map it to whatever action you want to achieve at whatever level you need it.
I'm happy to be wrong, but I'd be surprised.
I'm fairly sure that the price information shown on a Google Search result page is advertising that comes from a different source than the results do.
As far as I know, you could write a plugin for SearXNG to query suppliers and format the output as required.
I think that Google Shopping might be queried in the same way, but I've never looked into it deeply.