try to figure out if possible to make a PLE/Macro to select all stereo or mono channels.
for example to select all mono channels in project in one go and then insert mono plugin to that mono channels(for example waves NLS channel Mono)
The workaround could be to add a dedicated “flag” to your tracks names. Like [M] for Mono and [S] for stereo. Then, you can search for the Name > Contains in the PLE.
i actually thought about it too,but thought also maybe there is a way to do that with PLE.