I am out of my imagination. Maybe someone could help or have done this?
How to do sound of a squirrel running on a tree branches?
The shot is close.
Never actually tried it, but my first thought was just fingernails* on actual tree bark. Maybe the stuff you can get from florists - I quickly Googled 'florist supplies tree bark' & got a bunch of hits, cheap & easy to source.
It's going to be perhaps more resonant than a chunk of actual tree, but it might just be easier to get some mic levels. EQ out the low end if it feels a bit too much... or 'speed it up' the old fashioned way to shift the formants.
If you need leaves - then bay-leaf sprigs [the herb, laurel] could be sourced from the same place. Bay is really loud compared to most plants if you run your hand gently through it. The leaves are really firm & resistant.
*fingernails are always a good 'scampering' source, four on a hand, all pointing in the right direction... legs a-go-go.