With free basic features for full featured administration panel with security on laravel , FilamentPHP is a good option compared to the big brother, NOVA, also a good option from laravel developers themselves, but with a small initial cost. Let's have a look into a poorly documented FilamentPHP feature : multi connection table administration.
Once you know how to use multiple database connections in Laravel Models, you can use them to administrate multiple databases with single admin. The trick is to create folder based namespaces for your models and Livewire resources to identify quickly which database belongs to a pages, combined with menu structure via navigation groups.