Zenitco (and by extension the airsoft clones you see on aliexpress) quad-rails can be very easily modified to fit the T81 - aside from a little bit of a goofy appearance, given that the cuts are for an AK and not a T81, they're quite sturdy and a good alternative for a quadrail. On aliexpress these clones tend to be around 70-90 bucks. Similarly, the Yugo m70 airsoft quadrails you see on aliexpress can also be fitted - though they require a bit more work to do so, but are cheaper, around 45-55 bucks. I've fitted the zenitco clone to my LMG and it hold stable under fire with a vert grip mounted. In both cases, you will need to remove the wood from the gas tube (secured by a riveted plate), so keep that in mind.
To the best of my knowledge, there are no actual t81 handguards being marketed in Canada.