Did you know that Apple has an app for its symbols typeface?
SF Symbols is an app that can be used to search through and use the SF Symbols typeface and iconography. You can look through and download a variety of monochromatic symbols in a variety of weights. Of course, this is handy for developers, but you can also use the symbols in diagramming, and sometimes in other apps (e.g., writing), too. (It works for me in iA Writer on macOS, but not on iOS.)
Sadly they don’t seem to work here: ( ← that should be a thumbs-down…)
I haven’t bothered to do the research yet, but if someone knows offhand, I’d love to know why they won’t work in certain contexts. (I know it has something to do with available character sets.)