Design Review - nRF52840 BLE Application with Johanson Chip Antenna

Hi,

I have designed this PCB in KiCAD to send temperature and humidity data via Bluetooth. This 4 layer PCB has a ground and a power plane. Since this is my first RF design, I would like experts to please review this so that I can send the PCB for production.

I am attaching all possible images from schematics, layout till board manufacturer stackup.

GCPW is recommended by Johanson in their Antenna document. The width "w" and distance from the ground plane on top "s" has been determined by calculation estimations from Altium Designer and ChatGPT.

Regarding software, I basically have 2 question.
1. Can I easily program the nRF52840 and configure Bluetooh? Is it open source and free?

2. Can I be able to assign pins as per my requirement? Only GPIOs and I2C i mean?

Excited to see what experts have to say on my first attempt
Best regards