If pull requests were created that adds support for a platform other than the currently supported platforms what is the likelihood that such a PR would be merged assuming fit and function.
I think this question is better asked at the repo in question: dotnet/runtime, preferably including specifics (i.e. the answer might be different for a relatively common platform like FreeBSD or MIPS than for a platform you’re creating yourself).
Also, there have already been quite a lot of activity related to this, some links that might be of interest:
MIPS32 and MIPS64 support, where Immo Landwerth set the expectations (in 2015):
We do, however, want to work with others to port the code to more platforms. Our level of commitment will certainly vary based on roadmap, priorities, and overlap with other projects we’re already working on.
Tracking issue for Solaris x86-64 port work: this one shows very recent porting activity