Lego mostly here. DS is doing the 30 day Lego challenge with both his mate round the corner and his cousin in New Zealand! They make the same thing in the same day then WhatsApp each other the results - lots of variations and they are very very happy (although we've had to come together and brainstorm another 30 challenges as we've been locked up a month now
).
Minecraft.
Junk modelling with egg boxes, milk bottles, loo roll tubes, biscuit boxes etc. He's currently playing with his box-carten-loo roll "town" called Easter Bunnyville 
Science experiments from an awesome book my brother gave DS for his birthday. Science, technology, engineering, art, maths - fabulous book. You need ice, string, balloons, tape measure, random craft stuff. Easy to follow instructions. Lots of recording results and making pie charts etc - keeps him occupied a good two hours or so.
We have films and boardgames at night.
He must read to his toys at least 20 minutes a day (he is a book-avoider!).
Nerf gun fights with DH, and I made a big nerf target out of a cereal box,he gets points for hitting various triangles/squares, each round getting 50cm further back from the target - and he has to add them up! Maths, yay!
He hates reading, writing, drawing, colouring in. He doesn't have siblings. We're in a flat no garden. He hasn't left the house in a month. If he's bored, he pootles about.
I've just downloaded a stop motion app to the tablet, so he can start making Lego/Playmobil/war films for us to enjoy.
If he's bored, we'll stop and do something together, but both of us are working from home, DH flat out, me in the afternoons. We do Joe Wicks 3 X week and lots of obstacle course-type exercise during the day (Mission Impossible over chairs, under tables, step carefully through the minefield of plastic dinosaurs and pegs, that type thing).
It's exhausting, but you do what you can.
If your kids like drawing/colouring, could they make a story?