Sounds like the basics of searching have been done.

I would now try to find some companies that are seem like they have an urgent need for welders. Try calling them on the phone, and see if you can actually talk to a person. It looks like there's lots of people hiring: https://ca.indeed.com/Welding-jobs-in-Calgary.

If you're lucky enough to get someone on the phone (and I'd guess you will, if you call all the hiring companies), talk to them about sponsorship. Be prepared to tell a good story. Provide easily verifiable evidence of your skills.

It does also seem like there's a lot of scams out there. (https://www.visajobshq.com/post/construction-workers-needed-in-canada-work-visa-lmia-sponsorship-available). Maybe they're not scams, but they're selling a subscription to a product.