If you don't want to start your own community, I would say split it between buyCanadian for stuff you can buy today, retroTechnology and nostalgia to discuss and feature retro Canadian stuff, MapleMusic for music and EhVideos for films old shows or commercials etc.
Then outside of lemmy.ca promote Cancon to comics, art share since those are reasonably popular on Fedi. Then feel free to crosspost to !canada@lemmy.ca because all the Canadian folks here on Lemmy and Piefed tend to visit there.