If I remember correctly Microsoft did a bunch of studies back in the day and found the Calibri had some of the best readability across a range of visibility and reading impairments (like dyslexia).

Serif fonts have some readability features of their own, specifically for printed word.

One of the reasons Calibri was selected over Times New Roman was it has a lower rate of OCR transcription errors, making documents using it easier for people using screen readers.

This feels more like Microsoft lock-in than anything else. But I don't know how that conspiracy would actually work.

What is involved in changing the font for a government agency?

Anecdotal but the new default Office font Aptos seems much better than both TNR and Calibri.

On a screen, vs. Times New Roman? Absolutely, and it isn't at all close. Serifs on even the highest DPI displays look pretty terrible when compared with print, and lose readability tests every time they're measured.