there is something I do all the time, coz I mainly use Primal on desktop more than on my phone,

if it is a pic

1- just click on the pic to open it from the note

2- then right click

3- After right clicking, I click on "copy image"

and voila, I now have the image in my clipboard where I can paste it and share it wherever I want 😃

Hope this helps my fellow nostr user 🙏