Just upgraded to windows 11 but not sure about upgrading my Office365 to MS365

https://support.microsoft.com/en-us/account-billing/change-your-country-or-region-in-microsoft-store-5895e006-34f4-10f7-16b1-999e40adb048

From this article: "We recommend you change your region only if you're moving to a new country or region for a long time. This is important because items you get in one region might not work in another."

Of course, Microsoft Store is not the only place you can purchase Microsoft 365 subscription. You can even buy it in many retail stores (yes, subscription in a box :)). However, Costco in Canada was right about region problems. Read the article above.

Regarding Office 2019. Support for Office 2019 ends on October 14th. Soon. You don't care about technical support, ok, but you will not receive security updates!
Also, support for Microsoft 365 services connectivity (exchange, onedrive, sharepoint, ...) has already expired in 2023 for Office 2019. So, it'a good idea to upgrade.

Please, be aware about region and region change issues.