I don’t want to rehash the footway / path argument, so I won’t, but I suspect what people actually want to see on an “outdoors” map will vary greatly based on where they’re located, whether contours or hillshading would be an essential or an encumbrance, how footpaths / paths are mapped where they are and what transport they use.
As such it won’t be much use to mappers outside of England and Wales as it stands, but if you want to combine the values of various OSM tags (perhaps width, surface, smoothness, mtb:scale, sac_scale etc.) to create a “pseudo tag” to render, then those two repositories should show you how to do that.