Remotes aren’t usually actionable, so they don’t typically show up on the Alexa list of devices. As Paul said, you will create a virtual device, then you have the remote turn on that virtual device, and that virtual device coming on is what triggers an Alexa routine.
It’s sort of tedious to set it up, but a lot of people find it worth it to get the integration, even if it’s only partial.
There are detailed instructions in the community FAQ