Don’t know if this will be helpful, but I just made this shortcut for my own use and really like it. Super simple here but does the trick. Gives you a photo selection dialogue. Your choice goes to Dropbox, it grabs the link and formats and takes you back to Drafts with the formatted link in the clipboard. Once you’re back in Drafts just paste.
https://www.icloud.com/shortcuts/57ac887dd8934811bff7b7fc56151834