https://beourguestlunch.disney.go.com/
use your Magic Bands confirmation#. This is not tied to FP+ or MDE. I printed the screen at the end as there is no confirmation #
And this is probably cheating somehow, but it was mentioned on that other thread that if you don't have Magic Bands, if you click to modify your online checkin and look at the URL you are sent to in your browser, there is a long number as part of it. If you use that as your confirmation #, it works.
I did this last night and it let me make a reservation

No guarantees what they will do with it when I get there, since I don't have a MB, but if they don't, I'll just eat somewhere else.