Steam announcement:

https://store.steampowered.com/news/group/45479024/view/702141174212725149

Relevant bit:

Reservation details

Reservations will be limited to one Steam Controller per user.

Once you receive an order email, you have three days (72 hours) to make your purchase on Steam.

For now, customers who have already purchased a Steam Controller are not yet eligible to reserve another Steam Controller.

Additionally:

• Your account must be in good standing on Steam
• You must have made a purchase on Steam prior to April 27, 2026

Replenishment of inventory will vary from region to region. We will start fulfilling reservations next week in the US / Canada, and UK / EU / AU in the following weeks.

Not new. Same system they used for the steam deck. Just saying. Hopefully they learned their lesson.

Will the reservation be on the store page?

I assume so, but it doesn’t say.