You can use the signin API, however via the /beta endpoint. You can find some examples therein as well: https://learn.microsoft.com/en-us/graph/api/signin-list?view=graph-rest-beta&tabs=http#example-3-retrieve-the-first-10-sign-ins-where-the-signineventtype-isnt-interactiveuser-starting-with-the-latest-sign-in
Unfortunately, currently there seems to be an issue with the nonInteractiveUser category, but hopefully Microsoft will fix it in the coming days. You can still query other types:
GET https://graph.microsoft.com/beta/auditLogs/signins?&$filter=(signInEventTypes/any(t:t eq 'servicePrincipal'))&$top=10