If you rent your board, boots, bindings and helmet, you're mostly set. You should buy a pair of over the calf snowboarding socks, they cost 15 to 25 dollars. You can go to any Goodwill or whatever thrift (second hand) store they have in Toronto, and find used jackets, mid layers, base layers, beanies, gloves, and probably some non snowboarding winter boots which are nice for before and after riding. None of that needs to be snowboarding specific, just warm and moisture resistant, you'll use all that stuff in Toronto anyways. Snow pants are the one thing you do need, if you can't find used ones or loaners, you can buy lower end Amazon pants or a bib that are good enough for at least a dozen sessions. I use these and they're really good for the price, https://www.amazon.com/Arctix-Essential-Insulated-Overalls-36-38W/dp/B0032UJ2C2?ref_=ast_sto_dp&th=1&psc=1 For 40 bucks your won't believe how good they are. Good luck
If you are going to invest in "ice fishing bibs" get ones that have built in floatation. Otherwise, you are just getting fancy branded snow bibs. If you are cheap like me, these are perfect, lasted through 3 ice seasons so far. https://www.amazon.com/dp/B0032UJ2C2/ref=cm_sw_r_cp_apa_i_eKVLFb7XGRNW1
I have these bibs, but they're too warm, so I've only worn them a few times: https://www.amazon.com/Arctix-Essential-Insulated-Overalls-Medium/dp/B0032UJ2C2/ They're cheap, but good.
i got these as my first pair, they held up pretty good for my riding and are comfy they are a cheaper pair but for the price i was happy with them, https://www.amazon.com/Arctix-Essential-Insulated-Overalls-Medium/dp/B0032UJ2C2/ref=sr_1_5?dchild=1&keywords=arctix+men+snow+pant&qid=1603204907&sr=8-5