Updated 9/10/2020 from these sources:

• States allowing COVID-19 as a reason to vote at home are listed at https://www.vote.org/covid-19/ and KY (not yet at vote.org): https://www.sos.ky.gov/elections/Documents/2020GeneralElection/EO-GeneralElection.pdf
• States with inadequate safeguards are listed with 2 stars by NVAHI, National Vote at Home Institute, in a 5/13/2020 analysis: http://www.voteathome.org/policy-star-rankings
• Requirements to audit paper ballots are from https://VerifiedVoting.org/state-audit-laws, summarized at https://en.wikipedia.org/wiki/Election_audit#Overview. That source notes that CA, HI, WI do require audits, but HI and WI exclude absentee ballots, and CA excludes absentee ballots tallied after election day, which were 43% of total ballots in the 2020 primary. Some of the states which do not require audits have optional audits, or can release copies of ballots for outsiders to check the tallies.