Who is the tree of life for?

You say:

The tree of life in Revelation that is for the healing of the nations – who is it for, since all believers will have glorified bodies?   Will it be for the people who are here when the 1000 year reign takes place?

As you comment, believers will have glorified bodies, so they will not get sick or die.  The leaves would not be for their healing.  It would appear that the mortal population of God’s Kingdom (Zech 14:16) are the beneficiaries of the healing properties of the leaves of the trees.  However, it appears that the immortalised saints will eat the fruit of these trees – see  Rev 22:14:

Blessed are those who wash their robes, so that they may have the right to the tree of life and that they may enter the city by the gates.

These trees are also referred to in Ezekiel 47:

As I went back, I saw on the bank of the river very many trees on the one side and on the other.  (Eze 47:7)

And on the banks, on both sides of the river, there will grow all kinds of trees for food. Their leaves will not wither, nor their fruit fail, but they will bear fresh fruit every month, because the water for them flows from the sanctuary. Their fruit will be for food, and their leaves for healing.  (Eze 47:12)