What is the problem this feature will solve?

The overall aim is to have nice plot with proper ax.coords setting e.g. coord_wrap, format_unit, coord_type for custom Coordinate frames.

Currently half of the is supported, fitswcs.py supports custom ctype to UCD mappings via CTYPE_TO_UCD1_CUSTOM but then on the other side wscapi.py has a hard coded list in transform_coord_meta_from_wcs therefore WCSAxes doesn't recognise the custom UCD.

So currently this can be done

MYFRAME_CTYPE_TO_UCD1 = {
    "SXLT": "custom:pos.myframe.lat",
    "SXLN": "custom:pos.myframe.lon",
    "SXRZ": "custom:pos.myframe.z"
}
astropy.wcs.wcsapi.fitswcs.CTYPE_TO_UCD1_CUSTOM.update(MYFRAME_CTYPE_TO_UCD1)

but there is no way to include settings for custom:pos.myframe.X in this section of code

where Id like to add something like

            if "custom:pos.MYFRAME.lon" in axis_type:
                coord_wrap = 180.0 * u.deg
                format_unit = u.arcsec
                coord_type = "longitude"
            elif "custom:pos.MYFARME.lat" in axis_type:
                format_unit = u.arcsec
                coord_type = "latitude"

Describe the desired outcome

Be able to register or other wise include custom plot setting for custom UCDs in a similar manner to how custom CTYPE to UCD mapping can be included.

Additional context

No response