External display / mobile display on SailfishOS + Xperia possible?

Is it possible to run an external display via USB-C under SailfishOS?
There’s a couple of mobile display available on the market designed for usage with smartphones or laptops. This could be a nice alternative to a Sailfish tablet.
Has anyone tried it with a recent Sailfish phone, e.g. Xperia 10?

No. Needs changes to the compositor. There were some patches though.

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Do you mean an actual USB display device, or a USB-C->HDMI
adaptor type device?

From an end-users perspective: Anything as long as it works. Both type of displays exist as far as I see.

does the x10 support display output over usb-c hardware-wise? The xa2 variants afaik don’t.

Thanks for the hint, learnt something by searching for the right keyword.
Only the Xperia 1 and 5 series are capable of video-out. Even if SailfishOS supported it, the XA2 and X10 series doesn’t…

What about this link? Does the USB Type-C port support an HDMI connection? | Sony USA

These smartphones do not support directly HDMI (or Displayport or other video output) over their USB connectors.
So no way to send the picture directly to a monitor (even one with USB-C DisplayPort input).

BUT.

USB Displays are a thing (it’s an actual USB peripheral that shows on the USB bus, only zou can send graphics to it). Most of the phones on which Sailfish OS runs do support OTG.

There are just a few caveats:

  • the drivers for such USB devices displays are recent in the kernel, it might happen that the smartphone you’re considering has a Sailfish X baseport that’s way to old. (e.g.: that could be the case with Xperia X, which has a very old baseport on AOSP-6).
  • they aren’t just an extra screen to with the GPU send video, they are their own entirely different GPU (on that is connected over plain USB). So as mentionned by ApB the compositor (Wayland, the thing that send the windows to the GPU for displaying) must be adatped to handle multiple different GPUs.

(I.e.: from the point of view of sailfish, that would be as if in your computer, you plugged an Nvidia GeForce in addition to the AMD Radeon you already had and need to display on both.)