Solo founder works for B2C2B, and I think that's what you're looking to do based on what your examples.
Notion is actually the poster child for the strategy: you target a group of people who have the job title that'd use your product, but build something that appeals to them on personal level as consumers.
You don't bother with typical B2B messaging, no enterprise-y sales pitches, and you lean into community building.
That way your users will want to share it with their friends (who tend to be other people with similar job titles), want to bring it into their company for semi-personal-use, and eventually push for their employer to adopt it officially (and you charge them more for it as business users).
By the time you're face to face with the "Business", they've already established there's value in what you're selling and the signal is coming from the people they trust most.
