Pocketbook might be worth considering. While the eReader doesn't connect to OPDS, the iOS and Android apps do. You can add the book to Pocketbook Cloud, and it will be available on the Pocketbook eReader.
It's also easy to install KOReader, which has calibre client.
In theory someone could create a standalone OPDS client app for Pocketbook, but I don't know if anyone has.
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