Can I buy a phone outside of Koodo?

I currently have an Google Pixel 3xl, but I am planning to buy a new Pixel 7. I am also planning to buy the phone at Best Buy instead of going to my local Koodo retailer or buying it online at Koodo because I don’t know if buying at Koodo will change my plan. 

So I wanted to ask: if I were to just buy a new Pixel 7 at Best Buy and not Koodo, will I be able to just switch out my SIM card with no problem? Will I also be able to keep my current plan if I were to just get a new phone? Thanks.