I'm currently working on a project. I'm looking for free monospaced fonts that have built-in small capitals. So far I have found only the following:
Noto Sans Mono, and
Julia Mono. The first three are available on Google Fonts, the last on GitHub. My favorite monospaced font
Source Code Pro unfortunately lacks small caps and the designers said on their GitHub that they don't intend to add them. :(
EDIT: I have also found
Latin Modern Mono.