Is it possible to link two Google Ads accounts?

No it is not possible to link two Google Ads accounts on a single Branch Dashboard. However, you can still check the data from other Google Ads accounts by sharing the analytics.

You can do this by selecting the Share with another account Action in the Google Ads Linked accounts screen.

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The shared analytics data will feed into the other Google Ads account as if it is configured on their side.

Additionally, you can view the guide here on handling multiple MCCs.