Not a Walmart recruiter but I've talked to a few and I know how these screens tend to go. Also going through a search right now and just had my Walmart screen two weeks ago. Sharing both lenses.
The phone screen is 30 minutes. It's with a technical recruiter, not an engineer. Do not expect them to go deep on your code.
What they're actually checking: Can you explain what you've done in plain English? They're writing notes to pass to the hiring manager. If your explanation requires an engineering PhD to understand, they'll get lost and you'll get a vague "not moving forward" email. Why Walmart? This one is not optional. They ask it, and the answer matters. The trap is saying something like "great opportunity, big scale." The answer they want connects to something specific about Walmart's mission, the retail tech problem space, or the team you're interviewing for. Spend 10 minutes researching the Walmart Global Tech blog before the call. Logistics check: role level expectations, location / remote preferences, sponsorship if applicable, rough timeline. Behavioral warmup: usually one question. "Tell me about a recent project" or "walk me through your current role." This is your STAR story lite, not the full onsite version.
Questions I got specifically: What's your experience with distributed systems? How large were the teams you worked on? What's your availability for next steps?
Notably: no leetcode, no trivia, no gotcha. They're a filter, not a technical judge.
One timing note. Walmart's recruiting process can move slowly between steps. After my phone screen it was 10 days before I got an invite to the technical screen. Don't panic if you don't hear back in 48 hours.