Is WooPayments compatible with WordPress Multisite?

Yes, WooPayments is compatible with WordPress Multisite, whether the network is a path-based or domain-based one.

However, keep in mind that a single WooPayments account cannot be used with more than one URL at a time. As a result, each individual site in the network will use its own WooPayments account, even if WooPayments is enabled at the network level.