Hi. You can track multiple sites using one TM account. The only thing to keep in mind is to use the alternate namespace for the command queue. For details, please see this article (option #1): Can I use Piwik PRO and Matomo at the same time? | Piwik PRO help center
There’s also an example post with code examples that should work when consent manager is in use with cookieless anonymous tracking: Issues with installing Piwik PRO and Matomo on the same site - #7 by kuba
Note: both the guide and linked post mention Matomo, but in the end, it’s a really similar situation when you want to track additional property using the same TM container.