@noracodes from a tech PoV, i believe comradery.co might tick all those boxes now?

- supports monthly giving (non-tier, no tax) and tiered for exclusive posts (taxable)
- they added free newsletters a few months ago

it does not have a one-time payment option, if that's something you're after.

notably: they only permit certain types of projects!

@noracodes you are probably looking at ghost.
Here is a good list of alternatives https://buttondown.com/alternatives

Edit: I think both buttondown and ghost provide some level of help to migrate out of substack