Hi Pamela --
Your best bet may be the IMLS Public Libraries Survey, which collects data on all US public libraries annually. The most recently completed survey is 2021, but relative collection sizes will not have changed significantly in the last 18 months. There is a column in the data that counts eBook collections -- I don't recall the column heading name so you will have to look that up in the PDF with each survey that explains the data.
As to digital access for non-residents, this is a library-by-library policy and there is no single source that lists them. These policies will also vary widely by library. Some may not offer digital access to non-residents at all. Some will offer limited access through interlocal agreements with geographically-adjacent library systems. Some libraries are required by state law to offer access to everyone in the state. Every public library should have its policies posted somewhere on its site, though.
HTH!
Carmi Parker
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Carmi Parker
ILS Administrator
Whatcom County Library System
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