HOWTO: Connect a Nexus 5X to a PC

Previously on this blog I have bemoaned the apparent lack of support for the Nexus 5X on PCs. It turns out however that the connectivity is not well documented (not as far as I am aware with Android 8). Earlier efforts failed because I thought a driver was needed, of which no such thing actually exists.
If you are using Debian you generally need to install some extra packages to enable MTP support. However, it appears that MTP is installed by default in Debian 9.5, as my bedroom pc, which has been recently installed with Stretch 9.5, had no difficulty in connecting to the phone without any additional configuration steps needed.
Once the phone is connected to the USB-C cable, “Nexus 5X” will appear in a Thunar window (for Debian with XFCE) but there is still an additional step needed to make the file storage browsable on the phone, and annoyingly this option has to be selected every time you plug the phone in. Simply go to Settings, then open the Connected Devices section, and find the USB section. The options there are “Charge this device”, “Supply Power”, “Transfer Files”, “Transfer Photos” and “Use Device as MIDI”. It would be kind of nice if Transfer Files was the default instead of Charge this device, or if charge was able to be simultaneous with a choice of the other actions. On the other hand I find the other options interesting and might look into how they work. But given the limitations of the Nexus’s battery capacity I don’t expect to supply power to anything else anytime soon.
If you select “Transfer Files” then instantly the phone’s file storage becomes browseable and this will be a great benefit, not only in order to extract photos, but also store my music collection which has been virtually impossible to achieve up to now.
I assume the same steps will work on Windows 10 but am not rushing to try it because I don’t need the Windows 10 computer for much. I am planning to spend a bit of today finishing the incomplete reinstallation of the Windows 10 computer but I don’t need it for many devices and won’t bother putting any USB cables onto that computer, whereas I am connecting a full set of three device cables to mainpc because that is the most useful option.