Hello, I'm an archivist in the US. We are probably opening up our (smaller) archives to researchers in August, one researcher at a time, appointment only.

Are these a set of circulating microfilm? Generally that's not a big deal for ILL to get in, though these are almost always limited to in-building use only, which is the real problem, as libraries may be uncomfortable or unable to make a microfilm reader open and useable. Also, unless you are extremely cool, you probably don't have an at-home microfilm reader. But in-person ILL circulation is just starting to run again, as some libraries reopen to limited circulation.

The short story - you need to contact your ILL and work with them closely to see when you can start your research up again.