About the way to redesign the Space UI/UX, there is plenty of better alternative mockups on this board.
By @a44 from New Space Selector - sidebar / CTRL + Tab Switcher - #23 by a44
By @Marie.D from Bring back the floating mode for the side menu (and put the Spaces in a widget) - #30 by Marie.D
By @GrayArc from 🖌️ Improving Anytype UX: Redesigning Space, Account Interfaces and more