You cannot send 1 sat transaction without paying more than 100% fee in most realistic cases right now. And less than 1 sat invoices are not even supported by the wallets I played with.
I have written about this before for cases where somebody wats to pay for something every seccond, but currently this is not economically possible.

BallLightning

For all the talk of “fintech innovation,” small payments remain strangely broken. And small payments are actually most payments!

Banks are slow, expensive, and bureaucratic. Card networks appear fast, but only by hiding complexity and risk behind layers of intermediaries. And when it comes to genuinely small payments—pennies, cents, fractions of a cent—almost nothing works well enough to bother using.

This isn’t a temporary problem. It’s structural.

lightning

For all the talk of “fintech innovation,” small payments remain strangely broken. And small payments are actually most payments!

Banks are slow, expensive, and bureaucratic. Card networks appear fast, but only by hiding complexity and risk behind layers of intermediaries. And when it comes to genuinely small payments—pennies, cents, fractions of a cent—almost nothing works well enough to bother using.

This isn’t a temporary problem. It’s structural.