Have you looked at SharpTools? It may be able to show data from multiple hubs on a single dashboard. Tagging @josh from SharpTools who will be able to answer any questions about the product.
Looks like @garyjmilne has you covered. Yes, SharpTools can support multiple hubs in a single dashboard. Feel free to tag me if you have any other questions.
I have been trying this. Their instructions are not great, their error codes, are not great, their support pretends I don't know how to read and just reiterates what the error code says but doesn't explain why the product doesn't work when I follow the installation instructions.....