Does universal clipboard for work anyone? https://www.macworld.co.uk/how-to/apple/how-copy-paste-between-mac-iphone-3659951/ Copy a URL in Firefox on mac, doesn't paste in IOS. I guess the app must support it?
Update: it turns out that Handoff on my MacBook wasn't working until I signed out and in to iCloud. (Full diagnostic instructions can be found at https://www.idownloadblog.com/2016/03/15/troubleshooting-continuity-ios-mac/.) This then broke my Calendar until I forced quit it, and deleted the iCal preference as per https://discussions.apple.com/thread/8559377.