Switching to Public Sans solves none of the problems you're pointing out. According to the Public Sans's Github page, "Source Sans Pro" was the USWDS default,

Switching to Public Sans solves none of the problems you're pointing out. According to the Public Sans's Github page, "Source Sans Pro" was the USWDS default, which is a SIL font (so no licensing issues) and is also not in the OS/browser font stack.