Currently by default, it will be able to only search the current selected folder
In my desktop app there is an “All items” option which searches all folders and types. Correspondingly, in the browser drop-down there is the “My vault” label which shows when you have no folder selected, are viewing all folders. I checked also my phone app, which does the same.
What is the context which is not allowing global search for you? Is it only the key combination you are seeking? If so, what would it actually do, automatically change scope? Search is already progressive as you enter data, so there are no keys to press.
In my desktop app there is an “All items” option
You have to click this “All items” item before you want to do a global search, if you have already chosen some folder. Which make this more inconvenience is that I have many folders, so before clicking on that “All Items” item, I have to scroll to the top of the entire list…
in the browser drop-down there is the “My vault” label
For browser and mobile, current tab switch UX experience should be just fine, consider even we support hotkeys for them, such clients won’t use it as high as the frequency of desktop client uses.
This may depend on your setup for clicking in the scroll bar, whether clicking in the scroll bar moves by a page or moves to position. From a lower folder (“All items” concealed) it takes me two clicks to select “All items”, one at the top of the scroll bar and one on All items. I suggest this OS option as a workaround while you wait for votes on Cmd/Ctrl-Shift-F.
Also, each to their own preferred organisation of course, but I have found ‘organisation’ can be overhead. I sit in All items and use search. My half-dozen or so folders are there to differentiate a few areas for convenience of review one day, yet to happen. My vote has gone to this:
https://community.bitwarden.com/t/vault-item-labels-tags
where tagging can be used more flexibly to collect what one needs, if needed, instead of trying to do everything in a hierarchy.
I used to use KeePass, its supported both:
https://keepass.info/help/v2/entry.html
For me, having items in a hierarchy will be easier to manage everything, tag is only an optional field, I will only add tags to special items, and if convenience is a consideration, adding tags to the item will require you to use keyboard to type in many scenarios, instead of using mouse only to drag/drop items (into a folder).
And if you want to reveal all similar items with tags, you may have to at least remember all common tags you added for those items, then type them all into the search input, I don’t have such great ability to remember everything…
It is somewhat the point of tags that you do not remember to what you attached them… 
I believe we are not talking about the same usage assumptions for a password manager, especially in relation to desirable or useful levels of classification, and that discussion is a digression from your original request.
There is a mechanism for quick access to ‘All items’ search. Your request for hot-keys access stands in the market for votes. I meant only to assist as things stand now, not to downplay it.