Yes, YouTube Shorts can be effective to grow your channel. When done the right way, it can get you new subscribers really fast.
From my experience it's smarter to really focus on an actual video and make that go viral.
In addition you can remix the original video to a short and drive more views, to the main video.
For example: I started a new channel and focused on creating one good video. Now after 90 days, the video has over 600k views and 12k likes.
The channel currently got 2k subs as well. I was able to monetize the channel after 2-3 weeks already.
Quality is Key.
Shorts are an addition to the success.
But remember, when you post crappy shorts, you either attract traffic for that only,
or you won't have any success at all. So focus on branding the channel the way 1-10m channels are doing it too.