Scanning with the Canon mp620 with error code U163

Try to remove all tanks and insert them SLOWLY one by one. That's always the solution for an similar problem on brother printers.

The scanner in my HP F4280 AIO (admittedly somewhat dated, but not all that old) will work as long as actual cartridges are inserted into the printer and recognized as such, no matter what their ink level is.

However, don't take this as general advice that HP AIOs all behave like this. They might decide to change it at any time.

Furthermore, asking for specific manufacturers or products that support certain features is a shopping recommendation question and is probably off-topic.

I do not doubt your assertion that your Canon refuses to scan with no ink cartridges or when they are empty. This could be a simple programming oversight (a mistake), or it could be intentional. Unless you asked the original designers, it's hard to tell why exactly this happens. The intention isn't really important; what matters are the results. The fact is that you can't scan with this AIO while you don't have ink, which is a rather severe limitation.

Of course, if you're really in doubt, just buy a dedicated scanner and a separate printer. You'll never have to replace your scanner, unless you wear out the moving parts, or need a higher DPI; but in general they should last a very long time.