If somebody likes or boosts your Mastodon post, when you edit that post, they get a notification. So, by making the top of a Mastodon thread the “head” post, every time I add a photo, I edit the head post and people who boosted that post get a notification.
So, as an example, here’s the head post for my portfolio.
If you have a Mastodon account and boost that, every time I add a photo, you’ll get a notification.
And here’s the Mastodon sub-thread for the Rhug garden:
And the portfolio page for the Rhug garden