but for highway=pedestrian with vehicle=* I would still recommend to use oneway=yes for the vehicle part.
The more I think about it, the more I no longer want to deprecate oneway on pedestrian infrastructure and instead explicitly demand oneway:foot=yes/no if oneway=yes is present or if pedestrians should be effected.
This needs simply a check implemented in the editors and QS tools
highway=footway|pedestrian|steps + oneway=yes|-1 + !oneway=footway
only pedestrians oneway → oneway:foot=yes
only vehicle=oneway → oneway=yes + oneway:foot=no
vehicle and pedestrians oneway → oneway=yes + oneway:foot=yes