I am proposing a logical/stable way too.
But it looks like the base issue here is not about stability but about keeping both CMS work exactly the same instead of differently: “targetting users who switch existing sites from WP to CP and expect it to just work out of the box”.
Why not target “users who like WP and want to try something better for new sites” or just knowing that switching CMS will take some manual actions? That doesn’t mean unstable or illogic, it just means that you moved from CMS A to CMS B and that you need to do something about it. If you want everything to be the same then… well, don’t move.
I’m not here to change that view but just stating that from an OBJECTIVE point of view, wanting people to be able to switch existing sites from WP to CP is a very heavy weight to carry, leading to things like this:
if ( (is_plugin_active('woocommerce/woocommerce.php')) ||
(is_plugin_active('classic-commerce/classic-commerce.php')) ) {
...
… which is beyond crazy.
And it will get heavier and heavier as WP 5+ keeps evolving. And yeah, I don’t think such a thing can ever be successful (hope I’m wrong about that!).