Without Manifest V3 support, better to just use Firefox instead. Or, for Firefox extensions that are not specifically marked as Android-compatible, a fork such as Iceraven instead.

Most should offer alternative support options, even if they can’t promote them directly in their apps (an unfortunately anticompetitive practice), given that forking over 30% of a subscription’s cost to Apple or Google isn’t something I’d want to do just to support an app’s development.