Possible to link to Drafts (from other app) and auto-run an action or TextExpander snippet?

I have a series of separate journals I keep for my Weekly Review—each has its own TextExpander snippet. I have created Drafts actions that simply spit out the snippet text for auto-expansion, but would love it if I could click a link (from Things 3 task note in my case) and have the snippet automatically expand in a new draft.

Is it possible?

Almost certainly. If you have an action to create a new draft based that utilises your snippet(s), you can create a URL to link directly into running that action in Drafts.

Try using run Action, but drop the x-callback-url part of the URL to ensure you stay in Drafts and don’t jump back to Things.