Tesla has an isolation device but it only works on a string of 2-3 modules. If a string length is six then you might be able to use just two on the string ends. Not an optimal solution and only one racking manufacturer I know of has them as an option.
What I would like to see is a single SID that goes on the end of a string that can handle typical full string lengths, or a multi-SID box that several strings can pass through. After all, the idea is to have an isolation option with as few additional connectors as possible.
Their isolation device works with voltage up to 600v. The PVHCS restrictions, for the MCI-1 with Tesla's racking or solar roof, requires there to be no greater than 165v after rapid shutdown is triggered. Ironridge's racking certification does not have that restriction, and as long as it's 600v or less within the array boundary, you can use an MCI on both sides of the string to isolate the wires that go outside the array boundary.
The reasons the restrictions are different is due to the different ways UL and Intertek handle the listing. UL gets real particular about keeping the voltage under 165v, while Intertek seems to think that there are other ways to comply with the standard. Tesla decided to go through UL as the certifying laboratory, while Ironridge (and most everyone else) went with Intertek. Wheeeeeeee confusionnnnn
Also, other SID's exist like that. MidNite has a SunSpec-activated RSD combiner that Certainteed uses for their shingle certification, and Delta has their own SID (that I assume is not SunSpec) that works with their inverters and are listed for use with GAF Energy shingles. The stuff is out there, but there hasn't been a lot of cross-pollination between listings yet.