I don't want a situation where the mint needs to create millions of milli-sat tokens in advance.
I'd prefer to build a smaller set of tokens (1 millisat, 2 millisats, 4 millisats, 8 millisats, ... 1024 millisats ) in order that millions of different combinations are possible with only a small number of tokens.
At one moment in time, three of those tokens (1+2+4 = 7 millisats) "belong" to the router. Next, to move the balance up to 8, we need a way to send the 8 millisat token to the router, *where the router somehow revokes its access to the 1,2,4 -millisat tokens*. That's the challenge; the device gives access to a subset of the tokens, where the router can later 'revoke' its access (like in Lightning) in return for an updated - more valuable - set of accesses