I found it with DuckDuckGo of all things. The IAP search only found freemium and payware apps that weren’t great.
Others tried:
https://apps.apple.com/us/app/ithoughts2go/id918458207
https://apps.apple.com/us/app/coggle/id1187423011
https://apps.apple.com/us/app/fluent-mind-map/id645539191
https://apps.apple.com/us/app/xmind-mind-map/id1286983622
https://apps.apple.com/us/app/mindnode-6-mind-map/id12187180...
https://apps.apple.com/us/app/lucidchart/id611543423
(I can’t afford OmniGraffle)
Not as good as Pre-MS acquisition Visuo was, but I prefer Draw to MS Visio (though haven't used it in a while).
See: https://www.libreoffice.org or http://www.openoffice.org