Congrats on snagging the console! The storage struggle is real though. In my experience, the confusion comes from how Microsoft handles the new tech. To answer your main worry: no, you absolutely cannot play Series X optimized games (like Halo Infinite or Forza) off a USB drive. It doesnt matter if its the fastest SSD on the market, the console blocks it because it needs that specific architecture found in the internal drive or the proprietary cards. Tbh, its annoying but thats just how it is right now. Since your budget is $100, skip the expansion card for now and go for a high-quality external SSD. I use what I call the cold storage method. I keep my Series X games on a drive like the Samsung T7 Shield 1TB Portable SSD and just move them to the internal whenever I actually want to play them. It takes maybe 7 to 10 minutes to move a massive 100GB game, which is way faster than redownloading the whole thing. Plus, you can play all your older Xbox One and 360 games directly off that T7 without any issues. If you prefer raw capacity over speed, I have also used the Western Digital Black P10 4TB Game Drive for years. You can usually find the 4TB or 5TB version near your $100 limit. Its a mechanical drive so moving games back and forth takes longer, but you can fit like 100 games on there. Just remember, for the newer stuff, you move it to internal, play it, then move it back when you need space. Works like a charm once you get the hang of it.

Regarding what #2 said about "Like someone mentioned, the internal drive speed is..." - its exactly why you cant play the new stuff off USB. In my experience over the years, trying to cut corners with off-brand storage usually leads to corrupted data or drives dying right after the warranty. Since you only got a hundred bucks, I'd honestly look at Crucial X8 1TB Portable SSD 1050MB/s. Its super reliable and way faster than an old mechanical drive when youre moving games back and forth to the internal. If you just want raw space for like 50 older games, maybe go with Seagate Game Drive for Xbox 2TB External HDD. It wont be fast, but it stays within your budget and Seagate stuff has always been solid for me. Just remember anything with that XS logo has to be moved to the console to actually play... its annoying but you get used to the storage dance eventually. Stick to the big brands tho, dont risk your new console on cheap no-name stuff from the mall.

Like someone mentioned, the internal drive speed is just on another level. I love the Series X but the storage limit is brutal! Just wanted to add that you can totally use a basic external drive for cold storage which is what I do. You basically just park your huge games on the external and move them to the internal when you actually wanna play. Its way faster than waiting for a 100GB download, seriously. I think there are actually a handful of optimized games that still run off a regular USB drive, but I'm not totally certain which ones. Usually they have to be Gen9Aware or something... basically just upgraded older versions. Someone told me maybe some titles with FPS boost might work? Not sure, but its definitely worth a shot to save some cash! You're gonna have a blast with Game Pass tho, its amazing.