Decreasing PCTFREE on large table

Question about Oracle Database Enterprise Edition version 19.10.0.0.0 running as a standalone instance.

I have a table with billions of rows. The table has always had PCTFREE set to 10.

It turns out that we only ever perform inserts on this table, no updates, no deletions. I would like to save disk space by lowering PCTFREE to 0.

As I understand it, if I just do ALTER TABLE x PCTFREE 0 then in my case, only future allocated blocks are affected. But all the millions of existing blocks will never be filled above 90%.

Is there a way to get all the old blocks "re-evaluated" and put back on the freelist after I lower PCTFREE?