You can easily change launchers on the NVIDIA Shield and Chromecasts. Fire TV’s are really the only devices that actively prevent changing launchers and try to force you to deal with their advertising.

Personally my recommendation is generally the Shield, or maybe an Apple TV depending on your use case. Expensive but well worth it imo, you really do get what you pay for.

If you need cheaper, then I’d probably go the Chromecast. Lesser of the two evils between like the Fire TV imo.