That said, even for standalone devices, there's plenty of other data to target with. You can see the marketer-facing view here: https://advertising.roku.com/, https://advertising.roku.com/advertiser-solutions
On all Roku devices, these are collected and can be used for ad targeting (https://docs.roku.com/published/userprivacypolicy/en/us):
> We receive information about your interactions with the Roku Services, such as your browsing history, search history, search results, audio information when you use voice-enabled features, channels you access (including usage statistics such as what channels you access, the time you access them, and how long you spend viewing them), interactions with content and ads, and settings and preferences.
Like Samsung, TVs running Roku's OS use ACR and target ads based on that data:
> When you use a Roku TV with the Smart TV experience enabled, we use Automatic Content Recognition (“ACR”) technology to receive information about what live television content you watch via the Roku TV’s antenna, and what you watch via devices connected to your Roku TV, including cable and satellite set top boxes. For example, we receive TV viewing information such as the programs, commercials, and channels you view, the date, time and duration of the viewing, and how you use the on-screen TV guide. We receive TV viewing information both when you access live TV directly through your Smart TV’s interface and when you access live TV from within a Third-Party Channel. If the Smart TV experience is enabled on your Roku TV, we will use this information to personalize your TV viewing experience and ads.
