How to mitigate the risk of riding on highways
Google is probably not the best tool for this, it's not tailored to the needs of cyclists. I would always use BRouter, here is the route it produces when I ask it to give me a safe route. The route is quite a bit longer, but I'd guess that there are pretty few major roads without bike lanes on it.
BRouter is a nice tool that builds on OpenStreetMap data, and allows you to select (or even define your own) different goals (safety, fast, walking, non-hilly, etc.) for which the route is optimized. It even allows you to generate some alternative routes. I've found the results of the &quot;safe&quot; optimization quite solid, there have been pretty few places where I decided that the chosen route is not safe enough for my purposes.