An easy way I usually solve this with most MongoDB deployments is to have a couple data-serving nodes per shard that have local NVME drives and then have a hidd

An easy way I usually solve this with most MongoDB deployments is to have a couple data-serving nodes per shard that have local NVME drives and then have a hidden secondary that just uses an EBS volume with point-in-time backups. Your write load is already split up per-shard in this scenario, so you can horizontally scale out or increase IOPS of the EBS volumes to scale. And you can recover from the hidden secondaries if needed. And no fancy code written! :)