I am of the opinion that the public gateways field may not serve the purpose you have in mind. The developers of Kubo would be better equipped to provide clarification on this matter. However, based on my understanding of your objective:

• You possess content-addressed data on your local Kubo node.
• Retrieving this content through querying public gateways is not feasible.
• Your Kubo node is the exclusive source of this content.

If the aforementioned points are accurate, there are several potential courses of action:

1. Peer-to-Peer (P2P) Sharing: If you are amenable to allowing anyone to access the content in a P2P manner, you would need to execute a "dht provide" command for the Content IDs (CIDs) you wish your Kubo node to share with the network. This method is commonly used for content sharing on the IPFS network.

2. HTTP Provision: If you prefer to make the content available via HTTP, you must expose your Kubo node's HTTP gateway URL to the internet. This would enable external queries to access the content in the same manner as local queries, but through a publicly accessible URL.

Opting for the first solution would prompt the public gateways to detect that your Kubo node hosts the content and subsequently provide access to it through the public gateways' HTTP interface.

It is important to note that frequent requests may lead to public gateways returning 429 errors. If you anticipate a high volume of requests or require additional throughput or bandwidth, establishing your own gateway endpoint tailored to your application or use case is advisable.