Of course there is ways to get things done with large data sets. But we should always try to limit the amount of data where possible.
There is probably a way to filter the data coming from googlesheet for the last 7 days. Not sure though, as I always use a database if I am working with data like this.
To answer the question. You should probably get the data and then call a subworkflow to process it a smaller batch of items at a time. something like this
Make sure to clear your data at the end so it doesnt send all data back to the main workflow. you can do this by just adding a set node that keeps only set data. (and set it to run only once to be complete)