Was able to add on an additional connection leg of ANA Narita (NRT) to Chitose (CTS) for April, from Toronto on AC metal. The flight does not show up on aeroplan online search. Was on hold on the phone for 3.5 hours (no status). There was no extra point charge (which was supposed to be the case), and $46 of extra taxes and fees. Only took the agent 10 seconds to find the flight award availability I need (since I can see it on united). This is contrary to other data points stating "the agent may need to use a different system to look for ANA flight availability".
The agent confirmed that
1. ANA does not show up on the website, and people need to call in to book ANA
2. ANA Intra-Asia availability is very good
3. ANA long haul availability is "limited"

Of course, how one would interpret the word "limited" is up to debate.
There is a constant barrage of "conspiracy theories" here about Air Canada purposely hiding ANA availability in aeroplan online search to "force" you to pay for AC dynamic pricing on AC metal.
In my opinion, this doesn't sound very plausible.

This is because AC has no business doing Intra-Asia (or Intra-Japan) flights, so there is no "financial incentive" for AC to block these flights in aeroplan online search, but they are, completely blocked.
Yet, the agent was able to book this Intra-Japan flight very easily.
This means AC aeroplan does have access to ANA flights (at least Intra-Asia flights), but due to some specific reason, ANA flights do not show up on aeroplan online search.

My best guess would be that it is on the request from ANA to not show ANA flights on aeroplan online search, so people who really need to book ANA flights, they would call in.
This would definitely combat point brokers, as not only point brokers don't have 3.5 hours to wait on the phone, and furthermore, they can be interrogated by an actual person during the conversation, in an attempt to make sure the booking is not fraud and/or point broker.

Lastly, for "limited" long haul availability, there are a few data points that ANA flights show up on united and/or ANA mileage plan itself, but unable to be booked over the phone with aeroplan.