I was a part of a long-lasting "single-player" tabletop campaign (albeit with me as the player), so I know what you're talking about. What you're asking is essentially a 1x1 tabletop campaign, which is... well, 1x1. You might have better luck posting this check there since the 1x1 section is definitely more popular than the tabletop section, but either would work, honestly.

As for interest, who knows. I haven't seen much people asking or playing this kind of campaign on here.