In Pikmin Bloom, you can count your steps using two methods: "Track with Google Fit" and "Track with your phone" (Recommended). You can switch the tracking method within the game app by going to Settings > Privacy&Steps > Step Count.
If your steps are not being counted correctly when switch to "Track with Google Fit", please refer to this article.
If your steps are not being counted correctly when switch to "Track with your phone", please refer to this article.