Temporal doesn’t provide any guarantee around activity execution ordering. So it cannot guarantee that activity retries will be delivered in some specific order.
To avoid overloading a downstream service Temporal supports task queue rate limiting. When configured the tasks are not dispatched to the workers faster than the limit.
I was thinking of using a Kafka queue between Temporal activity and the downstream service, but this may be redundant.
I doubt that this would improve quality and availability of your system.