Yeah, the "Export" feature/functionality is not supported in CDS of PowerApps Community Plan currently. If you want to export a Entity in your Individual Environment (Comnunity Plan) directly, I afraid that there is no way to achieve your needs in PowerApps currently.
If you would like this feature to be added in PowerApps, please submit an idea to PowerApps Ideas Forum:
As an fixed solution, I think the Solution feature could achieve your needs. You could consider create a custom Solution in your Individual Environment, then add your existing CDS Entity into this solution:
After that, you could consider export this solution as a zip file. Then you could import this solution into any other Environment in any other tenant.
More details about Solution in PowerApps, please check the following article: