There is an Inert polyfill with all the information: https://github.com/GoogleChrome/inert-polyfill
The feature doesn't yet have a specification and hasn't been implemented in any browser.
See #2991.
According to ppl from Google there are Intents to implement it now:
https://github.com/GoogleChrome/inert-polyfill/issues/7
Quick update on this. We (Chrome) are now shipping inert behind a flag. We're taking the standard through the web platform incubation group process over at https://github.com/WICG/inert
+1
Edit @codl reaction
https://github.com/Fyrd/caniuse/blob/master/CONTRIBUTING.md#filing-issues
+1
Available at https://caniuse.com/mdn-api_htmlelement_inert
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Quick update on this. We (Chrome) are now shipping
inertbehind a flag. We're taking the standard through the web platform incubation group process over at https://github.com/WICG/inert