There is already a mechanism for post promotion built into Nexus.
We can probably just update it and change it to work however we like. It would be easy enough to integrate that system into the frontends since it's just an API call. I haven't studied the code all that much, but the way it works, if I'm not mistaken, is by sending some BLURT to @null with the post's author/permlink in the memo.
You can find the code where it parses payments sent to @null and update the promoted posts here:
https://gitlab.com/blurt/openblurt/nexus/-/blob/main/hive/indexer/payments.py?ref_type=heads
The promoted posts are already part of the bridge.get_ranked_posts API method. You just have to specify promoted as the sort parameter when calling the method.
The code for the bridge.get_ranked_posts method can be seen here:
https://gitlab.com/blurt/openblurt/nexus/-/blob/main/hive/server/bridge_api/methods.py?ref_type=heads#L74
I think that burning blurt is not good motivator for FE owner to pin ads. As FE owner usualy earn money based on the website traffic ex. AdSense.
in that case I see that we are closer to such a solution than I thought. only the issue of what @megadrive says on the chat that after 7 days it would automatically expire, in my opinion is bad. If someone pays, their ad should be up for as long as they are willing to pay.
This is an important point. If someone has something that doesnt lose relevancy in a short period of time they should have the ability to advertiser as long as they want.