but it would be really nice, if anyone could simply start developing a code for those applications using RFM69 or even Lora modules.
I think you have missed the point of my post , I don't think it can happen the pic environment is awash with veritable plethora of hardware combinations
the "simple" Arduino style libraries you seek exist because the Arduino is a rigid series of products , each one has a fixed osc ,fixed pin definitions ,
a fixed setup routine ,a fixed software shell , a fixed interrupt handler etc.... the user can change none of these things . the hardware is abstracted away from the user
hell even the pwm freq is fixed .you need some level skill to manipulate any of the hardware and the Arduino ide makes sure its going to stay that way and will
hide as much as it can from you