You can still have physical contact. I chase my kids around, carry them, watch the moon with them every night, wrestle them. You can long baths, play with bubbles. My two year old likes to creep up on her mother/sister and surprise them. Help them out with that.
Teach them to read. This isn't just "A- Apple, B- Ball." You can write text on your phone, like "dog" and Google keyboard will show an emoji of a dog. Or you can read out food labels with them. I count to 100 with my kids and it slows them down a bit.
I have a minimalist stash of food for the whole lockdown. But that includes lots of flour, yeast, eggs. We plan to make pancakes and donuts with the kids later. It's so cheap to do that it's almost free. If you want to get crazy and let loose, you can throw those eggs and flour on your spouse and kids (and have a good, long bubble bath afterwards).
This is a good time to pay attention to the little things. One of the upsides is no more commute time, so that just leaves you more time to mess around.
