Viva Goals provides a complete OKR platform that you can use to gain alignment within an organization top to bottom. One of the components of an OKR is a Key Result, which is the closest parallel to a PowerBI Metric. Setting up Metrics dashboards in PowerBI can give you a great view of numeric data, but it doesn't show as clearly how that aligns to an Objective or Key Initiative.
In Viva Goals, you may want to have the Key Results pulled from PowerBI, or any of several other data sources that have the numeric data. Viva Goals also does a better job of handling periodic metrics. Where the same measure is repeated on a quarter over quarter basis, that's easier in Viva.
The other thing to point out is that there is a difference between a Key Result or Key Performance Indicator and a Metric. There is often a lot of data that is worth measuring, but it is more often used to provide context than actual decision making related to an Objective. If your Objective is to increase profitability, then the Key Result is your quarterly or annual profit. Contributing to that though are likely several other metrics or measures like revenue, cost, etc. Similarly, if you have an IT Objective to meet an up-time/availability standard, then there is really only one Key Result that communicates success there. There are lots of bits of information you might want to measure though.
Treat Viva Goals as the top level tool.
Treat PowerBI as a source of Key Result data as well as a source of non-Key Result Metric data display.
