Using Microsoft & OUYA (& other Android-based consoles) as the historical reference & the adoption rate of AppleTV... it's generally NOT WORTH the hassles, especially as Apple (& Google to a lesser extent) is currently in legal battles with Epic Games.
Microsoft had problems getting the original XBox launched with some lackluster games (until Halo came out), quality control & design issues (remember "The Duke" controller?). Microsoft was generally throwing their money at the problem (the original XBox cost Microsoft $4 BILLION over it's market lifespan with 24 million units sold worldwide). Even the XBox 360 had a rocky start with QA issues (with the "Red Ring of Death", costing Microsoft $1.15 BILLION in warranty claims + a class action lawsuit) before turning things around.
Prior to XBox 360's second half of it's market lifespan once all the issues were fixed, Playstation & Nintendo fans were considering the XBox as nothing more than a business write-off for Microsoft. The XBox 360 had a similar thought pattern (especially with QA issues noted above), but was more respected as it was more in-form with competing consoles (PS3 & Wii). It took ALMOST A DECADE before Microsoft got the necessary respect from the gaming community (& rivals) in general.
One considerably failed console to look at would be the OUYA. While it had mass interest & raised a fair amount of money on Kickstarter (raising $8.5 Million) & only lasted for about 2 years before being discontinued (most mainstream game consoles tend to have market lifespans of 6-10 years). While the console was designed to be sold around $100, it was designed to be replaced in about 2 years with a newer model like cell phones... which is something that the home console community wasn't buying into. There was also rival clones like the Game Stick that competed against the microconsole as well as mobile Android devices (phones & tablets) paired up with a Bluetooth controller which practically assured the OUYA's demise.
The Apple TV a device that Apple already makes that can be paired with a controller like the SteelSeries Nimbus+ Wireless Gaming Controller to make a functional gaming console with the games you already purchased through the iTunes store as well as the Apple Arcade. HOWEVER, since all the games would be available on the iPhones & iPads, it has limited appeal.
I don't believe Apple would make a dedicated console since it would cost them a lot of money nowadays & it would take development resources from their other products. It's just something that Apple & their executives mostly likely won't do as it would burn through too much of the company's money & potential cost of customer goodwill to properly pursue.