I really found out Figma slide is very interesting, and I know it’s in a beta version though here is my thoughts and suggestion perhaps 
• when shifting in design mode using shortcut key(shift-D) it doesn’t show the layout grid tools/panel, but when you click it in the tool bar it will show, I think it’s a bug.
• Can we just remove the remove the round corner in slide itself, if doesn’t hide the overlapping elements or outside elements, or maybe had an option similar to regular Figma mockup design had a option to toggle hide outside elements 
• Create and able to create a custom brand templates instead of relying on pre-template made?
• able to connect or use the created design system from regular Figma design.
• Animation stuff unlike to powerpoint it’s more reliable to use powerpoint because capabilities of having lot of animation options.
• morph animation or smart animate, bind text properties to animate to next slide, specifically like letter spacing, font size, etc…
• add more animation stuff options
Hi there! Thank you for sharing your feedback on Figma Slide! We’ll pass it along to our team for consideration.
About the first feedback, the Slides team recently launched a Design mode shortcut (Shift +D), which should toggle your layers panel on/off, as needed. Here is the intended behaviour (if you can’t replicate it, please share a screenshot of what you see on your end):