How does Wholster handle inventory? Is it automatically synced with Shopify inventory?

Products within Wholester are pulled from the same inventory pool that you have set up in your Shopify account. This inventory is controlled solely through your Shopify account, and cannot be manually changed through Wholester.

When an order is placed in Wholster, inventory is deducted from Shopify as soon as the order has been confirmed. If the order is in an approved draft state, inventory will not be deducted until the order is confirmed.

If you need to reserve items for an order that is in an approved draft state, you can use the “Reserve items” feature on the draft’s page in Shopify:

To reserve the products included in an invoice or a draft order, click Reserve items and then select how long you want the items to be reserved. This reserves any items that have inventory tracking enabled, but doesn’t adjust their actual inventory levels in your Shopify admin.

https://help.shopify.com/en/manual/orders/create-orders

This will however only reserve the product from purchase on your online store, not Wholster, as inventory reservation information is not available from Shopify.