You're probably gonna have to drop ~$60 for a 1TB hard drive if thats what you want, plus the y cable. No way around that unless you find a cheap used one.

I have the older 500gb version of this one that I've been using for 7-8 years with a y cable. https://www.amazon.com/Passport-Portable-External-Drive-Black/dp/B07VTWX8MN/ref=sr_1_3?keywords=wd+1tb+passport+portable+external+hard+drive&qid=1650051151&sprefix=wd+1+tb+p%2Caps%2C78&sr=8-3. On sale in US for $48. I seem to remember the Wii U formats it when you first plug it in, so I'd assume it would work fine.

Or stick to the recommended list, as someone else suggested.