Help: Convenient Boot to Specific App

Hi, I was wondering if Roku or another streaming device can automatically open a specific app as soon as your boot up the streaming device?

My stubborn mom who is in her 70s and is used to watching Gunsmoke over cable since forever. She doesn't care for navigating streaming services. She recently had hip surgery and has to rest frequently, which is when she will watch Gunsmoke. This has forced my dad to keep paying for cable. But, he is tired of paying for cable and has recently he found a streaming service (IDR what it was called) that carries Gunsmoke. Unfortunately, he has to keep in mind her convenience.

If he could find a streaming device that can automatically open a service after boot, I'm sure it would mean a lot for him and my mom.

I appreciate your help.