Publish your deck (File → Share → Publish to web → Embed), paste the link below, and press Start. The slides auto-advance every 20s (GIFs animate). If the countdown isn't hitting 0 exactly when a slide flips, tap Space once as a slide changes to lock it — then it stays synced. Un-publish the deck when you're done.
Tip: for your screen-share, just share this browser tab — no fullscreen needed.
This runs entirely in your browser. The deck link you paste stays on your device — it's never uploaded, stored, or sent anywhere, and it isn't in this app's code.
Nothing is saved: no cookies, no localStorage, no analytics. The only external thing loaded is your own Google Slides.
The one caveat: to auto-advance at 20s, Google needs the deck published to web. Publish it temporarily and un-publish after your talk.