Is there an alternative for Time Capsule in the apple store?

Simple answer is "no".

Although Apple does not sell them, you might want to look at routers from Synology or Asus. These products have a USB port that will allow you to connect a USB hard drive which will support Time Machine backups.

So, instead of an "all in one" solution consisting of a router with a built in hard drive.....(the Time Capsule).....you will have a "two-piece" solution consisting of a separate router and hard drive.

If you don't really need another router, then take a look as a NAS product. Synology is recommended.

Nothing. It was a unique product.

Apple stocks Mesh wireless products from several suppliers. None of these even allow a hard disk to connect by USB. Nor do they have all that much Apple awareness even.

If you want a router that also can do backups.. our recommendations are

Synology RT2600AC.. this is the best but still very expensive and getting old. Synology has revealed nothing to replace it. Could it be a one product wonder.. ??

Asus higher end routers all support time machine.. BUT.. less reliable than Synology.

So for backup our main recommendation is Synology NAS. That means you can use any router or mesh system you like. And simply plug in the NAS. Even the cheapest unit will perform far better than any USB drive hanging off a router. NAS however are expensive.. at the same time they do last a lot longer than most routers.. and disks can be moved to the next model if they are not too old.