Will I be able to run Office 2011 for Mac Excel files on the latest version of Office for Mac on a Mac mini (M1 2020)?

Office 2011 will not work on any Mac (Intel or Apple silicon) that is running macOS Catalina, Big Sur or Monterey.

You will be able to open your Excel files using a current version of Excel or using other options below.

Microsoft does not provide free upgrades between major versions of their Office products (unless you subscribe to Microsoft 365) and older versions of Office are not compatible with macOS Catalina, Big Sur or Monterey.

If you have a version of Microsoft Office that is not compatible, you can either subscribe to Microsoft 365 or you can make a one-time purchase. See: https://www.microsoft.com/en-us/microsoft-365/mac/microsoft-365-for-mac

Or use the free and very good Libre Office https://www.libreoffice.org/

or the free Microsoft Office on the web: https://products.office.com/en-us/free-office-online-for-the-web

or Google Docs: https://www.google.com/docs/about/

or Apple’s Pages and Numbers