I was able to get the simulators to show up after manually launching the Simulator app (and making sure that I had simulators/platforms installed). After I manually launched the Simulator app, and opened a couple of the simulators, I rebooted. Then all of my installed simulators showed up in Safari. With that said, the removing of the device views is a huge step backwards. Make sure that you send feedback about this... Here is mine. I am not sure if you can see it or not. https://feedbackassistant.apple.com/feedback/13225118

I did a live stream about this last week in case it might help anyone else. This link should take you to where I start talking about the RDM. https://www.youtube.com/live/iAWa-mE3xcM?si=etM5-7mJxhX4eLCY&t=2491

The Safari dev team posted this today... https://webkit.org/blog/14670/simplified-responsive-design-mode/ My views are still the same. There needs to be some sort of function that allows us to quickly view a devices viewport natively in Safari. If the team did not like the "table" of devices, then change it to be a dropdown. I found the UX of the device table pleasing and different, but I will take a dropdown over nothing any day of the week. To add insult to injury. I spent an entire day getting the new simulators working last week. Now they magically are all gone. Xcode sees them as installed in the platforms tab. Sadly it's prompting me to install them again.

One more food for though item here... there are a vast array of user that "design" websites. I make software for website designers. I am definitely on the advanced side of the spectrum of dev tool users. I already had Xcode and the more advanced dev tools installed. But should we really expect an invdividual that is build a website for his local club to install Xcode and simulators? For these users, the device views are enough. As an advanced users, I know it's easy to forget about the more novice/light users. But we need to make tools accessible for them too...