Hi Gamula
I think that if you are using 'equivalence' then you are already stating that there are other items on the market that are pretty much the same as the one you're working on.
in this day and age, (for the most part at least) I think that a lot of mainstream devices are just re-hashed versions (updated if you will) of existing ones.
if you have something that is novel/new then you likely won't be using 'equivalence' as a tool (at least not in the initial stages).
it can be relatively easy to find information relating to other companies devices through simple searching (at least as a starting block), as many will put information (such as IFU, indications/contraindications and Intended Use on the mountains of paraphernalia that they upload to attract customers). you can then weed out the ones that are too different and only include the ones that are the most similar.
Equivalent devices can be those that are the same in theory, but in practice are for a different purpose (such as a different demographic, or body part); in which case this can actually help you with your justification.
so long as you prove that your device meets the Essential Requirements, then the 'equivalence' path should be relatively straightforward (well...you know what I mean LOL)
you're right, I can't imagine many (if any) manufacturers banding together and saying "yeah - we'll use each other's devices to do equivalence" (although it's a lovely thought!
)
does this help? or have I got the wrong end of the stick - in which case, apologies and i'll go hide under my desk