Speaking on the backend work involved and the infrastructure we already have:
A tipping/donation system (synchronized by Hivemind) can allow some flexibility to cater for what you suggest. Since tips or donations will be associated with a post by an author, we can leverage that post by adding some metadata.
What this implies is that we will have two types of donations:
Arbitrary tips/donations: non-commital, spontaneous funding that's mostly a result of people's appreciation. These are made on a normal post.
Goal-oriented donations: with funding goals, timeframes, etc. These will be made on posts that include some metadata.
So a post can "mark" itself as a "goal-oriented donation post" by including some JSON metadata, which the front-ends can pick up and then display the progress, supporters, time left, etc (as you've shown in your mockup) based on that metadata.
With the above, it won't matter if it's an entire site dedicated to donations or just a post within a community. The post itself will carry the metadata that defines what it is.
So an entire site can host only "goal-oriented donations" and focus only on that if it wants to. Or a community can just pin a "donation post" and that's it.
As a sidenote, I have been thinking about some possible solutions to the account security vulnerabilities that may be introduced if we predicate the tipping/donations system on the frequent/constant use of people's active keys. I have a couple of ideas and I will share those in that post I said I would make, soon.