We tried to use Paddle for our company but back when we were trialling them they didn't even have a dev environment (their suggestion was to create free products in production mode and use those to test dev/staging).
At that point I nope'd out of there and moved to Stripe.
But elsewhere they also still seem to recommend doing things involving your production site for testing purposes. That seems like it's probably a bad idea that could be risky if anything goes wrong and possibly mess up things like reporting and compliance even if everything "works".
I've been using their sandbox environment quite successfully for the last few months. Their main competitor, FastSpring, doesn't have a sandbox yet.
There's another interesting competitor that uses Stripe: https://getrevin.com. Their pricing is cheaper than Paddle, making them the cheapest I've seen so far. Not sure if they're any good, though.
I want to get some idea of how much it's going to cost but they dance around the issue completely.
All they do is recommend jumping on a call, which judging by the language on their site, will sound alot like talking to a stereotypical used car salesman.
At that point I nope'd out of there and moved to Stripe.