Linux distributions for Raspberry Pi, such as Raspberry Pi OS (formerly known as Raspbian) or Ubuntu usually come with a set of hardware-specific tools such as raspi-config and rpi-eeprom-update, which are used to configure the system, enable or disable hardware like SPI, update the firmware and things like that. These tools are missing in Ubuntu core.
Maybe that would be a task for a snap, although I’m not really sure whether this works in strict mode as required by core.
raspi-config is just a GUI front end to the config.txt file, you can manage everything by editing the file directly in Ubuntu Core (note that it is rather expected that Ubuntu Core systems are not used interactively, so the tool would not help a lot here, you’d rather ship your own gadget snap with adjusted config.txt file or the “defaults:” configured in your gadget.yaml)
i also think that @waveform actually works on a new yaml based config tool that will eventually be integrated with the existing snapd pi-config options as outlined at:
i tried to snap the eeprom updater tool before, but that will first require a new interface to actually access the hardware to allow a strict snap (classic is not install-able on core systems) …