There is a Labour Day Fair plus Market Monday at Burnaby's Village Museum: Admission is free
The last day for the outdoor Burnaby pools at MacPherson & Robert Burnaby Pools is Sunday September 3: Public Swims are from 1-5pm
The outdoor pools at Central Park & Kensington are free on Monday September 4th: Public swims are from 1-5pm
https://www.burnaby.ca/Things-To-Do/Outdoor-Facilities/Outdoor-Pools.html
There are a ton of other activies in and around Vancouver over the September long weekend, including festivals, music and much more:
https://vancouversbestplaces.com/labour-day-long-weekend/