heck something like this could possibly even be extended in the (probably far flung) future to include similar functionality for vsti...
The way I imagine the program doing this in the background would be it would do something like you or I would do to do this today : make a singular pattern with the number of channels specified in the popup window, play each note to completion in each channel, including some note off commands at some point, (maybe loops would have to be specified in some way), each channel is rendered to a sample, and then they are spread out over a single instrument's entire keyboard... All of this would be a lot of work to be done by the musician for each individual instrument at the moment - and yeah I have done this in small ways before myself...
Anyways I hope this suggestion is a good one.

maybe a more useful way to think about it would be as a bulk render to sample system that is specifically geared towards making usable instruments (as usable as is reasonable)... almost like a render to instrument system from opls and maybe in the future vstis... I think something like this was suggested for vstis a long time ago, but it does seem to make even more sense now for opls as well. I guess something like this, if applied to vstis would have to somehow know if the vsti is looping or if it has ended entirely, because from what my little brain cell has managed to grasp, vsts and vstis are a bit of a pain in the neck from the ompt host side of things so far since there isnt much commonality in the ways the internal programming of them are coded.
I imagine that also any effects applied to the opls (master) or the vsti will need to be bypassed for the rendering process.
I am generally just spitballing here guys, I do not think something like this would be trivial by any definition of the word, but I am wondering if it might be if only slightly easier than some of the stuff you guys have been saying are a problem for applying individual effects to opls, and it should solve a lot of other problems opls have by giving us decent to good renders of them in hopefully a few clicks, with some added benefits via the proposed customising...