I wouldn't have a concrete anything under a kid's playset! Except for perhaps concrete anchors at the ground supports. You'd need an awful lot of the softer material to offset the effect of a child falling off the swings. I can see broken bones and doctor visits in your future...........and maybe irate neighboring parents :-)

Many playgrounds have compacted soil beneath them that's almost as hard as concrete, so you could be fine. Do you have room for a foot of pea gravel or whatever covering you're thinking of?

As your baby starts to become more mobile, a baby gym is a great place for them to work on strength building and practicing movement. Laying on their back while they hold a toy, bringing both hands to their midline while holding a toy. A sports corner is an indoor workout facility that allows you to exercise in the comfort of your own home instead of outdoors. If the family raises children, it is an indispensable aid to maintain their physical strength and health. You can buy for this indoor play gym for toddlers https://ezplaytoys.com/collections/play-gym  Getting children to start being active at a young age is so important.