Yes, Wii U checks titles on boot, not on install.
That means no installed homebrew launcher unless signature checks are patched (like on 3DS)
smea already released sig patches though I thought, so it's more waiting for a coldboot IOSU loader, so those patches are applied at boot-time, right?
I feel as though the question should be, just loading a patched IOSU kernel (or whatever it is, too early to read memory from brain) wouldn't help with installing titles, as they would be checked on the next actual hard boot and deleted, or some other error/brick?
Either way the IOSU kernel needs patched for installing full titles with fake signatures or unsigned I'd assume. There are some other tricks to pull off without coldboot though, like emunand that would let you install stuff to the emulated space instead of the console. Since a kernel IOSU exploit is only one piece that's needed for a Wii-like experience of just boot and select shit, I wouldn't count on it soon. That said, I don't know how far SALT or anyone else is with coldboot hacks or IOSU, I just know work is being done. Not really in the loop.
Either way though, I'd much rather use the internal storage honestly than the SD card or USB, or emunand altogether. Every Wii U game I have and play almost fits on a 16GB card, leaving plenty of space to fill with other junk since mine is 32GB. Meaning they will fit in the meager space the Wii U provides on the 32GB console.
Correct my statements though if I'm wrong, just trying to remember everything from a few months back early in the morning.