It should be possible to connect ghost 6 to the fediverse, so that anyone with mastodon, lemmy etc should be able to comment, like etc
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Giscus / utteranc.es use github discussions/ issues to do comments so that might be an option
For one of my projects i setup remark42 which does allow anonymous comments. You can also set it up to allow logging in to a few different platforms. 7 months and no issues.
Isso is another one i had looked at which can do comments without an acct
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