We might save a few bytes (on certain platforms/chips) by using typedef to configure the datatype used to specify pin numbers on different platforms/processors.

For example:
in utility/ATTiny/RF24_arch_config.h

typedef uint8_t rf24_gpio_t;

in utility/ATXMegaD3/RF24_arch_config.h

typedef uint16_t rf24_gpio_t;

in RF24.h

    rf24_gpio_t ce_pin;    /* "Chip Enable" pin, activates the RX or TX role */
    rf24_gpio_t csn_pin;   /* SPI Chip select */

    RF24(rf24_gpio_t _cepin, rf24_gpio_t _cspin, uint32_t _spi_speed = RF24_SPI_SPEED);

I'm inclined to use uint8_t (as it was from maniacbug days) in RF24_config.h for any platform/chip that doesn't have its own utility/*/RF24_arch_config.h, but maybe it is safer to just use uint16_t for continuity.

Additional context

As usual, I have an ulterior motive here. In order to extend support to the zephyr project (which uses DeviceTree specs to declare GPIO pins), I would need a way to change what datatype is passed to the RF24 c'tor. By typedefing the gpio pins' datatype, I can more easily implement wrappers for the pinMode() and the like.