We're talking about ways to carry the rods so they don't get damaged in transit. The PVC tube most of us have mentioned is either a purpose built rod case or using what is commonly called a conduit carrier tube like you see on work trucks- normally workmen slide things like conduit, leveling rods, etc. in them but fishermen use them to carry fishing rods. They use a piece of PVC pipe and a set of end caps that affixes to them then some form of clamp to hold them to your roof rack. Examples: https://www.amazon.com/s?k=conduit+carrier+kit&crid=1AL1NC54CBETN&sprefix=condut+,aps,159&ref=nb_sb_ss_sc_6_7
I've never had problems with my rods banging around, but then I don't have >$100 rods anymore either. I've always just shoved a rag or piece of foam in to take up space before putting the cap on and it seems to hold them well enough.
I don't know of anyone who uses a rod case in the canoe itself but I suppose you could buy one of the collapsible styles so you could make it smaller once you got the rod out?
I never had a rod break in the PVC tube. The one I made is (iirc) 5" PVC so it can hold a number of rods. But with lots of bumpy roads I just worried about them rubbing on the PVC for extended periods of time (and FWIW I am using cheapie fly roads, no $800 Orvis rods for me....unfortunately! Ha!). I find it works well to keep them protected but as I said earlier I live the idea of something that would allow safe transport while keeping the reel in place and line ready to go.