I have a lot of different 'sweet' moulds & my son loves making chocolates.
For kids entertainment I use the big bars of chocolate from Lidl (Fin Carre? I think it's called) & get white as well as milk chocolate.
It's less than 50p a bar & you can make quite a few chocolates from one.
Melt a bit in the microwave, coat the moulds & let it cool.
We fill them with random stuff such as peanut butter, fruit, Nutella or ice cream, or whatever else my son comes up with at the time.
Depending on how old kids are, you can do more complex designs incorporating stripes or swirls of white chocolate.
Then once filling is set if it needs to, just coat bottoms with chocolate, let that set & you have your own sweets.
The peanut butter ones are actually really nice.
They won't look as nice as properly made chocolate or have the perfect shine, snap etc..., but it keeps kids entertained for hours for very little cost & they look/taste okay too.
We also make Easter Eggs using moulds (they are cheap on Amazon) then pipe decorations on.
Once you've made them, you have a treat to give them too.
Also things like Ninjabread or Gingerbread men (depending on your cutters) take up time both with the making & the decorating.
My son also spends hours designing the perfect gift box to put sweets & biscuits in & making it. (This usually involves zombies in his case it doesn't have to be 'girly')
Cost being felt pens & some light card plus a bit of paper for the contents sheet like you get in a box of chocolates sometimes.
We also have quite a lot of kits to make all sorts of things from animations, lino printing or tie dye, to sets to build lots of different working circuits if you get them right or mechanical models, remote controlled robots etc... chemistry kits (we get monthly) to do experiments with VR lessons & quite a few unopened Lego sets which would each take a couple of days to construct.
Honestly though as we are EHE, my son would just keep doing his normal lessons for all the academic stuff & just not go to the group activities.
There are plenty of online resources for every subject at every level you can imagine.
Look at places like Khan Academy for a start (free) or some of the many free sites that offer lesson plans & activities to teachers.
Just because they are at home, doesn't mean they can't do a project on something or other.
Keeps them occupied.
I won't make fudge with kids because of the high temperatures involved.