Is it ‘allowed?’
The question could be better constructed.
It can be - if the chair wants it to be.
Why would a chair not want it to be?
Maybe if disruptive, distracting or delaying?
If it adds value and makes a worthwhile contribution - why wouldn’t a PC want public participation?
If a PC has lost touch with the community, forgotten that they exist to serve and has become aloof and disengaged then perhaps restricting public participation would be desirable.
I suspect there are a great many PCs that would be grateful if any public even attended a meeting. If someone takes the time to attend why would you set out to disenfranchise them? What would be the benefit of that?
A local meeting should seek to serve local interests. If allowing public participation serves that purpose - embrace it, why on earth would you not?
There certainly aren’t any rules / regs that bind a PC - it must decide for itself.