Can someone delay tovelling a set of new dishes (for pesach) until after everything comes down and mikvehs start opening up again?
Nope. If you want to use the dishes they need to be toveled. You can dip them into a lake, river, or ocean as well.
Is there any requirements to toveling in a river? How big does it have to be?
Any natural body of water is good.
But we are not allowed to leave our house except for food and medical reasons.
Of course it follows that all the rules of social distancing etc. should be followed, but what is the difference between a food store and a outdoor natural body of water? I would think the item one needs for eating (utensil) should not be different than the item one eats with that utensil.
MORE IMPORTANTLY, IF WE ARE TALKING ABOUT DISHES, MEANING CHINA, THEY DO NOT NEED TO BE DIPPED. Only all-glass dishes, steel, silver need tevilah.
Since it was brought up, how would one kasher China then?
As far as kashering is concerned China has the same rule as glass , because it has that glaze on it that will not allow it to absorb.
Therefore it does not need to be kashered.
And yet it may still not be used for milk and meat, rather pick one and stick with it.
What about a crock pot insert? can that be used for Pesach? If used with disposable plastic liner does that help?
crock pot inserts (the old fashioned crock pots) are very hard to clean and remain perfectly smooth, and /or crack free. If it in fact is smooth then you do not need to do anything. If it has a crack we are fearful that it absorbed chometz flavor and then it would be problematic to say the least.