I feel like this is a great approach for bootstrapped and/or solo founders. Break the idea that some of these markets are huge defensible spaces requiring bootstrapped funding and higher teams.
The ironic thing is I know there's been other 100% bootstrapped 'calendly-like' software made in this space (over 10 years ago no less).
savvycal is a personal favourite of mine, even if it's a commodity service, good user experience isn't