In reply to Lankyman:
Yikes - I can't imagine Cowal and Long Covid being a great mix! My partner is finally recovering from it after the best part of 3 years and has informed me that she won't be going anywhere near Cowal for the forseeable. Maybe I have told her too many scare stories about the trees and vegetation in the past....
I think Mark has covered some of the best hills, but you may also manage Cruach nan Capull based on what you have done already. I remember it being a bit squelchy but if you approach from Corrachaive Glen in the north and get onto a rather wet path through the trees at around NS099808 then you can get clear of the trees without too much hassle (well you could 8 years ago). The summit is good for views down Loch Striven over Bute and Arran. I ended up carrying on to Cruach Neuran by some firebreaks but you may be best retreating the same way.
Sgorach Mor is probably a more interesting summit but I'm not so sure how easy it is. My memory of it was more pushing through trees and following boggy quad bike tracks but the Clachaig Hill flank to the south looks to have been felled and may have better tracks onto the high ground now - pure speculation by me though.
I like Cowal as it is rugged and has sea lochs and I don't really know it that well, but I'd rate it as some of the toughest terrain in the country alongside some of the Galloway hills.