You are correct. You cannot limit where individual fields are shown, only entire field groups.
It is possible to limit where a specific field is used by using an acf/prepare_field filter to remove fields that should not be shown. You would need to use the “field key” variant of the filter and you would need to determine for yourself when the field should be shown or not.
In all likely hood it would mean saving the post to become effective. For example, if a location rule is based on a taxonomy term then the post would need to be saved with that taxonomy term before you would be able to test for that taxonomy in your filter function. The same would apply to any setting that is generally controlled by WP.
This could be overcome by moving all WP settings into custom fields, you could then use conditional logic based on these new custom fields instead of the above filter. However, this would mean creating an acf/save_post action to convert all of the new controls into WP setting when the post is saved. This may also not be possible in all cases.
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