You can use the image factory to achieve this. The image factory is a tool that allows you to create custom Talos images. You can find the documentation here.

You can also use the endpoint to generate images. To achieve this, you need to adjust the schematic.yaml file to include the extension you want to add to the image and then run the following command:

curl -X POST --data-binary @schematic.yaml https://factory.talos.dev/schematics

Then you can use the ID and the current Talos Version to get the image URLs with extensions:

https://factory.talos.dev/image/<ID>/<VERSION>/hcloud-amd64.raw.xz.
https://factory.talos.dev/image/<ID>/<VERSION>/hcloud-arm64.raw.xz.

Use these URLs in the talos-hcloud.pkr.hcl and replace image_arm and image_x86 to create the snapshots with the extensions.

You can create a file hcloud.auto.pkrvars.hcl to overwrite the default values. The file should look like this:

talos_version = "v1.7.4"
image_url_arm = "https://factory.talos.dev/image/98b430833db447e791fa9fecb915073eb8a6d85ccf80ca3f67cd3bf56c527f49/v1.7.4/hcloud-arm64.raw.xz"
image_url_x86 = "https://factory.talos.dev/image/98b430833db447e791fa9fecb915073eb8a6d85ccf80ca3f67cd3bf56c527f49/v1.7.4/hcloud-amd64.raw.xz"