That hole in the pipe will be useful. Buy a floplast strap boss from Screfix
drill a 40mm hole in the pipe (encompassing the damage) like this (not central, offset to be "round the bend")
and use it as a spy hole while a helper flushes the toilet
I expect you'll not see a rush of water past the hole, in wish case it means the blockage is upstream of it
pinch the end of a garden hose down into a u shape and put a trimmed cable tie or electrical tape round it
(to make more of a spray nozzle- reason I recommend this rather than a big hose lock nozzle or whatever is that this can go round corners and doesn't get snagged, or if it does you can just yank it and pull it back. Anything bigger or more substantial may become wedged or lost in the sewer system or not go round corners. This way the most you lose is a cable tie),
feed it into the spy hole and push it upstream, have a helper turn the hose on then helper watch the toilet bowl while you continue to push, wriggle and jiggle the hose upstream. If you start getting paper etc passing you you're succeeding in breaking up the blockage.
You can also do the same trick from the toilet end, "jetting" the drain
When you're done, take your strap boss and line with a bead of silicone, insecure it in place with the strap. If the strap doesn't reach, cut the teeth ends off, drill holes in it and use a meaty cable tie through the two holes to secure the strap. Block the hole in the rubber bung with anything that's solid and 32 or 40mm and stick it in
You have essentially turned your broken bend into a bend with rodding access:
For much less than what one of these babies costs
(But if you want to buy one and cut the access out and glue it into your pipe, go for it
Soil pipework is not under pressure and having an access on a bend like this is often helpful