That’s quite a collection!
There’s no direct integration between Insteon and smartthings. (I know you know this, but for other people finding this thread in the future, the two companies are competitors using different communication protocols.)
Back in 2016, there were some Community members trying to use the insteon API to create an integration, but there hasn’t been any activity on that for several years, and I’m guessing that some of the changes that smartthings made to tighten up security may have killed that integration. You can take a look at that discussion thread and see if it gives you any ideas:
It’s particularly challenging right now because smartthings is in the middle of a big transition: new hub, new app, and a new cloud is coming. So it’s hard to say what will or will not work in the future.
At the present time, I think the most popular integration is just use either IFTTT or MQTT as a “man in the middle.“ It’s pretty simplistic, but it may give you some options to get through the current transition until we know more about what the new cloud will be.
As far as dashboards for Insteon, I would ask in the Insteon forums.