Question: Is there a minimum tx fee? I know there's a minimum relay fee, so a 0 fee tx won't propagate(?). But what if I mined the block myself?

no min then :)

you ofc have to propagate the tx as part of the block, which could be slower

why? If it is a valid block

others don't have the tx

so higher risk of being orphaned?

so that tx has to be sent before they accept the block fully (mining the block allows skipping the min relay)

yes

So the block will not be accepted with unkown tx, - but the tx cant be relayed so it will never be a valid block (beyond your private chain)

it will be relayed as part of the block

just, not before you mine the block

ok, tnx. So a mining pool could do 0 fee payouts as part of their own blocks

it has been looked at for p2pool

Huh? aren't p2pool payouts part of the miner tx?

it was considered for aggregation, specially after FCMP++

see monero-project/meta #1296 logs

ah ok, so a p2pool perk

there's nothing stopping others (past going below the min range) from doing that but it wasn't well liked :)