My little boy was 18months when lock down happened so a bit older but here are things I did that he enjoyed
Blow up some balloons and hang them at varying heights hanging down from the ceiling for him to bat and run through (fully supervised due to string and potential risk of strangulation of course)
Fill some zip lock bags with water and food colouring and tape them to windows for him to have a squish at
Make a posting game (I styled mine on the hungry Caterpillar as it was his face book at the time - slit in lid of a coloured in formula tin with cardboard food) like a box with a slit and different sized envelope or shapes
Tough tray with shaving foam, big toy jewels and sequins
Bath in the dark with glow sticks in the water and music
Use masking tape to mark out roads on the kitchen floor for his cars
Make a slope with a big bit of cardboard and roll cotton reels or toy cars down
Ds when he was little also liked the job of moving tea bags from a bowl into the jar and back again and on the subject of kitchen activities - get your spices out and let DC smell the different types
Home made playdough
Bring outdoor toys inside if you have room (IE little slide) and use sofa cushions to make obstacle courses