To confirm - and to add to - Jon's comments about the stretch from Metig to Greenbush:
We came east from Greenbush in late August 2023 with low water conditions. We could not find the portage mentioned in Todd's 2018 video so stayed with the river. We lined the top, were able to float a bit of the middle, and then spent quite some time dealing with the bottom set of rapids. We each put a canoe pack on and dragged our canoe through this section. We spent about 90 minutes getting from Greenbush to Little Metig. It must have taken Jon much longer to move upriver!
https://albinger.files.wordpress.com/2023/12/from-greenbush-to-metig.png
Once on Little Metig we paddled over to the marked campsite, figuring the portage trail would be nearby. After walking down a couple of dead end trails, we paddled up along the shore looking for the longer portage trail. After a half hour we gave up and stopped for lunch at the campsite. Behind it is a garbage dump left by locals, who would seem to make regular use of this site, perhaps for net fishing.
With lunch done, we figured we were in for a repeat of the morning's slog. Amazingly, we were in Metig Lake within five minutes. It had been an easy C1 float down!