Sidecar via WIFI unusable and nearly impossible via USB

Context:

• Apple MacBook Pro (15-inch, 2018), macOS Monterey 12.6.5 (I reverted after noticing that Ventura grinds the machine down to a near halt).
• Apple iPad Pro (12.9-inch) 1st generation, iOS 16.4.1 (a) (still running strong, frankly better designed and built than the MacBook Pro, by a long stretch!).

Problem:

For the past 2 years wireless Sidecar has been awful (after a few seconds it would freeze, and show the unstable connection warning), but unlocking the iPad, switching to its home and then back to the Sidecar app would trigger it to automatically switch to USB, and everything would be fine.

For the past 4 months it has been a hassle to get the iPad to engage in USB Sidecar. I would have to do the following:

• Unplug any and all wires from the MacBook Pro and from the iPad.
• On the iPad go to Settings / General / Transfer or Reset iPad / Reset / Reset Location & Privacy.
• On the iPad go to Settings / Wi-Fi and turn it OFF, go to Settings / Bluetooth and turn it OFF.
• Restart the iPad.
• On the MacBook Pro go to Library / Preferences / SystemConfiguration, delete preferences.plist and NetworkInterfaces.plist.
• Restart the MacBook Pro.
• Once both devices finished rebooting and logging in, connect the USB-C to Lightning cable between them.
• Activate Sidecar by clicking on the Screen Mirroring button in the top menu, and selecting the iPad from the drop down list

I would have to do this every time I disconnected the iPad or disengaged Sidecar. This means I would do this 5 times a day on average.

For the past 2 weeks now this doesn't work either: roughly 50% of the time the iPad doesn't show up as an option for Screen Mirroring (either in the drop down menu from the top bar, or from System Preferences / Displays.

I have logged out of, and back into, my Apple iCloud account on both devices.

I have reset the VRAM on the Mac.

This issue has survived all the OS updates that have taken place in the timeframe I indicated (the only one I am avoiding is Ventura because it is evidently not designed for Intel Macs).

Now... we all know too well that Apple has been lagging behind more and more in terms of software quality. We also know that Apple has likely decided that support for Intel Macs is a low priority, but I collectively spent 6 thousand dollars between the iPad and the MacBook Pro. I expect them to work!

Does anybody have this kind of issue, where even a family-sized mix of most workarounds together don't fix the problem??? If so how on earth do you get these bloody machines to do what they are supposed to?