I just logged into steam again and tested to confirm this worked for me, I can open the launcher and click "Play" from my library and then change settings and close the launcher and then load the game through F4SE and it runs as expected.
What I also did was delete the "downloading" and "temp" folders in the "steamapps" folder with the game's appmanifestID ("appmanifest_377160" minus quotes) since i accidentally opened steam first and it began trying to update.
I then un read-only the appmanifest for a moment so I could edit it, opened the SteamDB link, and in the appmanifest file (I opened it in Notepad++ since it's Much cleaner it's meant for code) and I used control+F to search for each of the installed depot's numbers on the steamDB's page, then opened each link in a new tab to avoid refreshing the steam DB page constantly, then I went down to the line for the ManifestID (You can use control+F to find it) then I copied the long number for that and pasted it in the part in quotations beside "manifest" in that "installed depot" section of the file. It might be a little bit tedious, but do that for each installed depot area's manifest number in the file and when steam checks that against it's databses it thinks the game has the newest versions of the base game and dlc.
You Must make the appmanifest file read-only after this, and before doing this Backup the Original appmanifest file to restore it when you're ready to let steam update the game for the smoothest update process possible at the time. Sorry for the long post, the steamDB is probably a confusing part for a lot of people so i wanted to be a little more detailed there since there's a lot of entries on the steamDB page and it looks overwhelming (did to me too lol).