Current workaround using AutoHotkey (on Windows):
; ZOOMING BY NUMERIC KEYBOARD PLUS AND MINUS
#IfWinActive ahk_exe Obsidian.exe
^NumpadAdd::^= ; Ctrl++
^NumpadSub::^- ; Ctrl+-
#IfWinActive
Related feature request: Enable Ctrl+Scroll or gesture on touchpad to change zoom in common way