[Select] Fails when using screen reader or keyboard navigation

While generally the accessibility functionality of the MUI Multi-select is decent, it would still fail any audit due to inconsistent screen reader behaviour and keyboard navigation. See further details below.

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behaviour 😯

Screen Readers (SR)

Win10/Chrome/ChromeVox

When I navigate to the select that has preselected entries, these are not announced to me unless I open the menu and navigate to each of the entries. It is possible to open the menu and select/deselect ok with enter key, space doesn’t work. No instructions for the user either, and the select is announced as a ‘button’ and I’m not informed when menu is expanded or collapsed. Not an ideal experience. Would fail an audit.

Win10/Chrome/Jaws

Slightly better experience (announces as expanded, gives instructions to navigate list), but JAWS won’t announce which of the entries have been ticked/selected. You have to close the menu and listen to the chips to determine that. Would fail an audit.

Win10/Firefox/NVDA

Can navigate menu using Insert+Space, then arrow keys, however selected entries are not announced, as per above. Would fail an audit.

Mac10.14/Chrome/VoiceOver

Shares the same issues as above. Would fail an audit.

Overall

• SR doesn’t announce which of the entries have been ticked/selected.
• SR doesn’t allow user to use spacebar to select/check entries.
• SR doesn’t always announce when the listbox has been expanded or collapsed.
• SR doesn’t reliably read the selected entries when the menu is collapsed (e.g. chips)

Keyboard Navigation

It works with TAB to select, up/down arrow or Enter to open and Enter key to select entry, but doesn’t work with space to select, this would be expected behaviour.

Expected Behaviour 🤔

• SR must announce which of the entries have been ticked/selected.
• SR must always announce when the listbox has been expanded or collapsed.
• In keyboard navigation mode and while using SR we must allow user to use spacebar to select/check entries. See HTML5 example: https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select

Steps to Reproduce 🕹

Try the following example with the above mentioned screen readers and using the keyboard only: https://cwvg4.csb.app/

Context 🔦

The goal is to meet the WCAG 2.0/2.1 AA standard as legal audit requirement for a learning platform used by millions of students, teachers and administrators.

Your Environment 🌎

Tech	Version
Material-UI	v4.9.10
Browser	Firefox (latest), Chrome (latest)
Screen Reader	Jaws, VoiceOver, NVDA, ChromeVox
OS	MacOS 10.14, 10.15, Windows 10