Please excuse the late reply. In general, Icinga does not build packages for distributions which are end of life. Sometimes there are exceptions, for example when releasing a security fix. Unfortunately, the Icinga » Subscriptions » Support Matrix page is outdated and will be fixed soon.
Sorry for the confusion.
And by soon Alvar means now 
Your suggestion with the end dates looks pretty good. I’ll discuss it with Blerim - his initial reaction was that it might get a bit convoluted and hard to read. So we’ll look into how to make it clearer and more informative.
Thank you for the suggestions @moreamazingnick !
@theFeu
can you look into sles-15.5 / opensuse-15.5 too?
according to the supportmatrix it is supported.