Need to show my Mac desktop (no remote control, preferably free) to multiple PC clients
Apple’s screen sharing is designed around security, so having multiple views in would be my last resort.

How about something like Skype for Business / MS Teams / Google Hangouts. None are truly free - you are selling access and attention to Google if you use their option and Microsoft charges for O365 to host the meeting tools. There are dozens of other collaboration tools like Slack that also enable sharing as well as the vendors like WebEx, Zoom, GoToMeeting, TeamViewer and handfuls of other startup / smaller collaboration tools.