I guess its possible to aggregate the clicks via /v2/sp/{recordType}/report and /v2/hsa/{recordType}/report e.g. with the compaign dimension. But since there might be row limitations, I wonder if there is a simpler way to get account or at least profile wide metric values, e.g. for clicks?
No, i think not.
Currently you have to aggregate the data anyways because it is only possible to request data for one day per request. Performance data is only returned for datasets that have at least one impression. So on campaign level it is very hard to reach row limitations if there are any (i did not yet reached any limit with the reporting service).
For the keyword report i get definitly a lot more than just 100 rows (just tested).
And btw.: API endpoints beginning with /v2/hsa are deprecated. Use /v2/sb instead. https://advertising.amazon.com/API/docs/en-us/info/release-notes