So not all that terribly long ago, a display driver was added to the kernel called "GUD"; https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/gpu/drm/gud?h=v6.0.11
Conceptually, its very similar to "displaylink", except that (1) all of the components and protocols are open source, and (2) the open source implementation only requires about $5 in hardware (a raspberry pi zero).
Has anybody done any research into this? It would be a brilliant feature to have available on GrapheneOS.