We do have a build-in feature to achieve your requirement.
Azure DevOps commit history also supports advanced filters that allow you to view various history of the repository, branches, or files with various levels of granularity to support complex scenarios.

Azure DevOps supports advanced commit filters such as :
- Simple history
- First parent
- Full history
- Full History with simplified merges
But this only apply to a branch of a single Git Repo which is largely restricted.
In our official feature suggestion website, here has exists such feature suggested: How do I view the history of all branches in GIT?.
Note: You can vote and comment there. When has enough votes, the Product Group will consider it as plan.
Though it could not be achieved with UI, here has another work around you can try. You can use Rest API to filter the commit history by author within all branches.
Here is the sample:
GET https://dev.azure.com/{org name}/_apis/git/repositories/{repositoryId}/commits?searchCriteria.author={author name}&api-version=5.1
This API can list the commit records with the author filtered across All branches.
For multiple repos, you need to combine the returned results together.
As another choice, you could also pull the whole repos down and use Git Command to query related info.