Among the videos of home-training etc I haven't yet seen any mention of the potential of trees during the lockdown. Despite living in Birmingham, close to Spaghetti Junction, I'm getting a lot of climbing-fun from an oak tree in a patch of woodland. Circling the whole tree, swinging under or round every main bough, is an excellent 'traverse'. Other old trees have small lumps on the trunk which give good crimping. Of course, rotten branches are as dodgy as loose rock; if leaves aren't growing, treat that branch as a 'forbidden hold'.
When reading the thread about Foot & Mouth, I remembered that in 1967 aid climbing was more popular, and I was shown a tree with a large horizontal branch where the local climbers used to practise with slings etc. I haven't tried this yet, but you might be able to do this as a tye of 'via ferrata' even if you haven't got a belay partner in isolation.