Would a time delay mechanism help do you think? A bit like some e-mail have an insensitive button for about 30sec after you hit send.

Perhaps you can optionally set safety rails for yourself in a client. E.g. you choose a “delayed send” time, 5, 10,15,30,60 sec then when you click post it shows in your local feed with a clock icon. Until then you have the option to click the icon and unsend/edit it. After which it pushes the content to relays.