Probably the only time I would consider needing a chest rig is when wearing a pack with a hip belt in brown bear country where I would want to carry a full size firearm.
When wearing a pack in most of the places I hike and camp I use one of @Craig6 ’s belly purses (fanny pack turned to the front) or pocket carry. I did recently pick up a belly band that I’m thinking of using in these situations but haven’t tested it out much yet.