If she's travelling there already and will be there for a while, it should be possible. (Travelling there specifically to submit would likely be a lot more difficult)
This is the hard part. I'd suggest contacting VFS in USA as well as the consulate/visa office there, although can also try Delihi. Don't know whether you can 'arrange it in advance.'
Note: I think you will get a negative reaction if they think she is not yet in the USA (i.e. if it sounds like travelling there just to submit).
Hey so i contacted VFS in USA. They gave a response "Kindly note that the passport request letter is valid worldwide, unless that the letter specifies that the passport needs to be submitted in a specific place. If you have a legal status in the United States, and have received a Passport Request Letter, you can submit your passport to one of the Visa Application Centers in the United States." From their response it feels like we are ok to submit it.
Also, I spoke to IRCC call center, they suggested to write a webform to New Delhi and describe the situation. I just submitted the webform with her USA travel date and temporary address there and about submitting the passport in USA. I got a generic response -
"Due to the increase in COVID-19 cases, lockdowns and curfews have been imposed in various parts of India, which may impact VAC services. If you have already paid the 2-way courier service but have not yet submitted your passport, please hold on to it until services resume. If you have submitted your passport, it will be returned to you once the passport services resume."
They haven't acknowledged the fact that I want to submit it elsewhere and instead responded with their auto reply template
Any suggestions?