Microsoft released a new Office that's compatible with Apple's new Big Sur OS and the recently announced Macs featuring M1 processors. So out the gate, Microsoft Office should run on the New Macbook Pro, MacBook Air, and Mac mini without issue.
Thanks to Apple's Rosetta 2 translation software, the M1-powered Macs can run x86-64 code written for Intel Macs. Microsoft covered how it will work in its announcement.
In the announcement, Microsoft mentions that there are some performance considerations in regards to running Office via Rosetta 2, stating, "The first launch of each Office app will take longer as the operating system has to generate optimized code for the Apple Silicon processor. Users will notice that the apps 'bounce' in the dock for approximately 20 seconds while this process completes. Subsequent app launches will be fast."
According to Apple, running apps meant for Intel-based processors via Rosetta 2 is just a temporary solution and in the near future, it is expected that developers create software that natively runs on Mac's new ARM M1 processors.
To that end, Microsoft reiterated its intentions of porting Office to the new Mac architecture so it runs natively, "...we've already started the process of moving Mac apps to universal binaries. In the future we will natively support both Apple Silicon and Intel chipsets within the same executable."
It appears we're entering a new age of processor innovation with Apple once again leading the way.