Unlike other open source SDK projects for the PS1 that have come and gone, the main goal of the PSn00bSDK project is to develop a 100% open source SDK for the PS1 that tries to be on-par to the official SDK in terms of hardware support. While PSn00bSDK is still a work in progress, it was fit enough to create n00bdemo as it already has the best graphics and 3D support on the hardware compared to other SDK projects that I'm aware of. Other components such as SPU, MDEC, controllers/memory cards and especially the CD-ROM have yet to be implemented fully so proper homebrew games can be made with this SDK.
Screenshot of n00bdemo taken from pSX/psxfin:
Another thing about PSn00bSDK is that it follows the same library syntax as the official SDK as closely as possible not only for familiarity reasons but also to make it easier to port existing homebrew made with the official SDK over to PSn00bSDK with little to no modifications, provided the functions it depends on have already been implemented.
Progress on this project has been pretty slow lately mainly because this has been a one man effort so far and life's been getting in the way a lot for me lately. I also haven't finished working on the video about this SDK project yet either.
Webpage (has more info regarding features and a download of a Win32 build of the GNU GCC 7.2.0 compiler targeting mipsel):
Github repo (has more info and build instructions):