that sounds good to me. a couple of questions:
-by default all plugins in a chain are simply connected as now and as i adjust them with those commands i change the routing, right? because in most cases the default routing does actually just work.
-how do i adress the audio before it hits the first plugin, so that i can send ch1 to two mono plugins in series and then to a stereo plugins left input while connecting ch2 directly to the right input of the stereo plugin? and how do i address the final out? would slots start at 1 for plugins and 0 would be the adc? and last pluginslot +1 would be the dac?
-related to question one, this will not allow me to "load" 20 plugins and only connect the ones that i need and don't eat all CPU, right? they all will be active, it is just the routing that is dynamic. (that is absolutely fine with me, i can still have several lv2host instances...)
ingen does have a method to create lv2 plugins from lv2 plugin-chains. so you basically open up a patch, add all plugins you want, route as you like and then save as lv2 plugin. you can then load that as a plugin in ardour(open-source daw) for example.
a similar approach would also be nice for bela but the one you suggest is probably more flexible