I have recently discovered the FiraCode font which provides additional programming ligatures . While FiraCode seems to be the most popular font in this style, there is also a fork of DejaVu Sans Mono which provides this feature .
Please consider adding a DejaVu Sans Mono variant which provides additional programming ligatures.
(It doesn't need to be a whole duplicate of Sans Mono. Instead, it should be sufficient to only provide the ligatures in a separate file and add a fontconfig rule to prefer Sans Mono for all the other glyphs.)
Request at the fork's issue tracker to separate out the ligature glyphs into their own SFD files: