How to connect a frame buffer to an LCD monitor through DisplayPort or DVI in an integrated system
Displayport/DVI/HDMI are pretty much variations on a theme (That theme being very fast LVDS signalling, think Gb/s on each pair), and if the micro does not have a suitable port directly, the usual answer is a small FPGA with some DDR to hold the frame buffer interfaced to the micro over some suitable interface. 
This is a pain in the arse if you do not do FPGAs as while it may look like programming, it is really not. 

I would suggest that the smart approach for this sort of thing is to cheat, put an ethernet port on your machine and use a tablet/laptop/phone with a web browser as the interface for anything that you cannot run from a local SPI driven display. 
Something with a web browser is probably more readily available then a monitor, and you want ethernet anyway so you can do SNMP for status and control. Web development types are ten a penny compared to VHDL folks for video interfaces, and your micro probably already has a IP stack/web server/SNMP server ported to it.