yes, there in pd just do
[integer] -> [s midiCh]
(just to be clear, the mother host in no way filters midi etc, all midi messages go to PD, and then mother.pd filters, so the above is simply telling mother.pd which channel to use)
also we should be clear this channel selection only affects the midi to organelle generated mapping e.g. midi note -> organelle 'key’
there is nothing stopping you using PD midi objects which will ignore the ‘selected midi channel’ (unless you want to filter them) … this for example could be used if your patch wanted to be used on multiple channels. e.g. from different controllers.