Treasury API works only for Govt/Debt securities. Another alternative is to use OpenFIGI. It supports lookup by many identifiers including CUSIP.
To access the API key, it requires an institutional email id for sign-up. Free email accounts such as Gmail/Hotmail are not accepted. That is a small caveat.
Google and bing now provide apis though ggl is very limited. I would then use data science happy languages like R or python. Some examples that may help clarify what and how; Tampa times has pinochio-meter. https://old.reddit.com/r/dataisbeautiful/comments/et90ci/oc_100_seconds_to_midnight_analyzing_3_years_of/ https://old.reddit.com/r/dataisbeautiful/...