Currently we cannot return all information at trademark search, as that endpoint is highly scaled for search operations.
Serial endpoints are best to retrieve the raw values of a trademark entry with all history. You can use serial search and batch calls if you want to retrieve these details.

Thanks for providing the answer. Would it be possible to make this a one step process? Meaning, the return values for the trademark, where you return the serial number as part of the trademark search output, also provide its classification information? This would prevent me from calling a separate API (using the serial no.) just to find the classification. Thanks for listening!

there is a similar answer posted here: https://rapidapi.com/pentium10/api/uspto-trademark/discussions/95194

Could you please review that. In case you cannot find the answer there, please look at this full ouput details and reply back what is missing for this specific serial number. https://pastebin.com/UzHNjUQx

We could analyse further if something is missing for you.