No Series X required, just Game Pass Ultimate

If you're intending to get the Fire TV Stick specifically for Xbox Cloud Gaming, I'd recommend you spend the extra $10 to get the 4K Max. It has the most powerful processor, but more importantly, it supports the Wi-Fi 6E protocol. The speed and reliability of your internet connection will directly correlate with your cloud gaming experience.

That's why its usually worth holding off until one of the big sales periods, such as Black Friday or next week's Prime Big Deal Days at Amazon. Xbox Wireless Controllers are generally a lot cheaper around then. In fact, as a bit of a bonus, Amazon has heavily discounted them already as part of the build up.