Bored 9 year old

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Just wondering how much activity/action is normal for this age group on the weekend?
I think my 9 year old needs more structured activity on the weekends (e.g. a sports team/group) to help pass the time and boost his mood and energy levels. Too much time spent lazing about and on screens. My partner thinks his routine is fine and we’re busy enough.

During the week he has a sports activity on 2 week days from 5-6.30 and wraparound school care 2 days, 1 day he comes straight home at 3.30.

Current routine Saturday and Sunday is generally a dog walk/out on scooter for an hour each day. One weekend day will visit grandparents and the other weekend day he will usually go with one parent to do errands. Might go to a birthday party/go swimming/see cousins once a month. Rest of time is at home (a lot of screen time, but will draw and read, or play cards with a lot of encouragement). Spring & summer is easier to manage as we can get him out in garden easily to play with sibling or have days out.
In the background my partner and I are busy with shift work/other child/house work/gym - so we don’t have much free time ourselves.
However I do feel we should be getting my son out and about more. He’s tried cubs/scouts but didn’t enjoy. likes sports and has friends at school but don’t really socialise much outside of school.
Any thoughts ?

Why is the assumption that if he isn’t out doing things he will be at home on a screen?

we strictly limit screen time to an hour a day max regardless of what else is on. Some days they are busy and don’t get to use their entire allowance, some days they have had their hour before noon and then get to experience boredom. inevitably there is a bit of whinging but their options are to find something to do or be given something to do. I do a bit of baking or board games with them, but I don’t feel like I need to keep them occupied all weekend.

It’s not the assumption, but it is his default activity of choice if there’s nothing else specific happening (in the winter anyway). In spring/summer the tendency is to go in the garden kick a ball about or go on trampoline etc.
I think an alternative activity is needed as an alternative to screen time rather than just go cold turkey on it, preferably something where he socialises with peers. We do instigate card games, suggest play in bedroom, but it’s hard work.