the closest not floss option I've found so far is
https://ellieplanner.com/
I say this because it has the to-do and calendar integrations I want and it has a one time purchase option
god I hate that we live in an age where one-time purchases are disappearing
that being said, the one time purchase option is a hefty $150.
I do not have $150. I want to have $150. If you find $150, thanks.