Nice project manufacturers datasheets, RF appnotes etc all mention this, with results for different usecases (like gnd plane size etc). I mentioned it a few times on the forum: nothing under or near antenna (keep out zone) their matching circuit, and CE/FCC certif are based on their development boards+their antenna if external, often without enclosure. there are a very few pcb antennas which are resilient to untuning. ceramic or meandered pcb are usually more compact but less resilient (like when you approach your hand and device suddently has better or worst communication) once you change any of these parameters (board shape, gnd size, enclosure etc), it breaks FCC, and may need retuning, still you can get useable range. "ideally" tuning should be done once enclosed for example. manufacturers can't cover all cases. on my side, I try to follow these rules. and when interested in a design or a device, I check this. Mainly the routing+gnd, antenna choice, keepout zone, and orientation vs my usecase (long range needed or not for example)

Please Is it possible to buy only PCB? Do you plan also to release your sketch?

hello @berkseo can you share sketch for this sensor ? i am very intrested about this thank you PS: great job !

Can you tell something about the range of this node? And do you see a chance to post the schematic?

I think you can just set the I2C pins in MyBoardNRF5.h without remapping the pins in MyBoardNRF5.cpp. Look in MyBoardNRF5.h, under the Wire Interfaces section. Set SDL and SCA to 30 and 31 as appropriate for your board.