Yeah, not every Developer Options menu is going to have all the same features as every phone has its own unique hardware configuration and some manufacturers will include/exclude options in the menu.
Previously, when you were able to just mount your phone to your PC, in the Windows Device Manager any chance you noted if the USB driver was shown as Huawei, or Google, or Android? Windows drivers for USB devices don't get defined all that well at times. And looking at Huawei's site for a Windows driver just confused me even more:
https://consumer.huawei.com/en/support/phones/p20-lite/
https://developer.android.com/studio/run/oem-usb
-- and just some reminders in case you haven't already tried them
Try using a different USB cable
If you're plugging your phone into a USB hub, try plugging it directly into a USB port on your PC
If you're plugging into a USB 3.x port try a 2.x one if there is one, or vice-versa.
Also, since WiFi isn't an option, have you tried Bluetooth connectivity?
https://www.technipages.com/transfer-files-between-android-windows-10-via-bluetooth
Bandwidth speed will probably noticeably slower but works as a 'last resort' option. If your PC doesn't have Bluetooth support, an adapter is pretty cheap.
Or you can always just pick up a basic wireless router. Plug it in and connect your phone and your PC to your own little local network. Online access isn't a necessity, a typical consumer router will be fully functional as is for your own, isolated from the Internet, network.