Firefox can't override "<input> picker was blocked due to lack of user activation" in about:config

When I try to programmatically click a file upload button in Firefox with document.getElementById['myId'].click(), I get

picker was blocked due to lack of user activation.

I see in the Firefox source code

InputPickerBlockedNoUserActivation= picker was blocked due to lack of user activation

in the console. I tried setting InputPickerBlockedNoUserActivation to false in about:config. This has no effect, and I'm still blocked.

Is there a way to override the block on .click(), or is there something I'm not understanding about InputPickerBlockedNoUserActivation?