Complete working Braintree js / php example works like Paypal Express Checkout?

I'm trying to figure out if it is convenient for the customer to switch from Paypal Express Checkout to Braintree, but I find the latter too complicated and difficult to understand (terrible docs, only links are good).

The documentation does not contain COMPLETE WORKING examples, with all the required pages where you can simply change the API credentials and everything works. This is essential for any system / API to get the logic and workflow quickly.

Basically I currently have a checkout system with all my customer details and cart_id with a form to redirect customer to Paypal passing all that data and as soon as the customer completes the payment Paypal forwards the url on my server sending all sent by me the data plus the transaction id, and thus I mark that basket_id / order as paid and assigned the transaction to it. And no sensitive payment data is printed or passed through our server / network.

How to do it all in Braintree js + php? Any full and complete sandboxed desktop where I can just change my credentials and have working code to understand the logic? This is much faster than reading the honestly rather convoluted documentation.

Thank!