Yes. Xapien works in the browser on your phone or tablet. There's no app to install: open platform.xapien.com in your mobile browser and sign in as usual, including with SSO or MFA.
What you can do on a small screen
Start a report. Identify and report set-up have been rebuilt for small screens, so you can kick off research from anywhere.
Read reports in full. Tap a report card to open it full-screen.
Check sources. Tap a citation to open the source panel and follow through to the original.
Use Ask Xapien on a completed report by pressing ≡.
Things to note
Xapien is a web application only, so you won't find it in the Apple App Store or Google Play Store. You can add platform.xapien.com to your home screen for quick access.
A current version of Safari, Chrome or Edge gives the best experience.
Large exports and detailed comparisons are still easier on a bigger screen.