I've been cursed with collecting a couple too many bikes, and a pretty compact storage space (I won't pretend it's a garage, let's just admit it's the bike shed). About two years ago I just couldn't take it any more and invested in a system called "Space Rail" from a UK outfit called Stashed. This was after an run with traditional hardware store thread-in wheel hooks. It works a little bit like at the dry cleaners where the wheel hooks hang from rollers, and the bikes can be pushed around and even rotated to get to the ones I want.
There is a big caveat with ebikes: a single Space Rail hook has a limit of 65 pounds, and each rail section is rated to hold 220 pounds. And you've got to be willing & able to lift those 65 pounds to the height the wheel hook is mounted at. It becomes more complex when there are a lot of bikes in the way (or anything on the floor to trip over

). I tend to hang one of the lighter bikes in the middle that I can more easily remove to free up a little room to maneuver the others. But only my two lighter ebikes get hung. I have two 65 pounders that live on the floor with my cargo bike. I suppose I could park them up there in a pinch.
For my installation, I have 3 full sections of rail plus a shorter section to fill the remaining gap†, and a total of 13 hooks covering roughly 13 feet of space. I can hang the bike from my choice of front or rear wheel, handlebars in or out, whatever needed to make 'em fit. I favor hanging the heavier bikes from the rear wheel because the front wheels like to flop over when lifting the bike, requiring a hand to control it. The height of the system can be rigged with basic carpentry skills to be at whatever height is convenient and useful, but the company suggests a minimum mounting height of 82 inches†† to be compatible with the typical range of bike wheelbases.
I met the founder of the company this past spring at the Sea Otter Classic in Monterey. His company rented a booth in the expo. He told me that the US is their biggest market, and I can tell you that he has the shipping down cold. I've ordered three times from them (once for extra mounting brackets, and the last time for an extra rail to fill the gap), and each time I received my boxes in about 3 or 4 days via DHL, packed super neat, all the parts sorted and a breeze to assemble. I voluntarily added extra mounting hardware due to my joist design, but he looked over my pics and thought none of that was necessary -- but I would have done it this way anyway.
The system is not perfect. I still have to lift the bikes, and the kids are only mildly successful working together and with a small step platform. There are handlebar / wheel / pedal conflicts to work out. But for this many bikes in such a small space, it's tons better than anything else I've seen or tried.
† I started with three full sections of track, but was left with a 13" gap to fill plus a friend offering me his gravel bike, which conveniently turned out to be the only bike that clears the top of the air compressor! So later I ordered a fourth section of track, and I cut it and the third track both shorter to put the joint somewhere in between -- each section needs at least two brackets to hang from. These track sections are each just shy of 48 inches, but from what I'm seeing on the Stashed website they have decreased their length to 44".
†† As noted the mounting height needs to be a function of the longest bike's total length (not just the wheelbase). So for instance the cargo bike will always live on the floor, and you'll never see the tandem unless you look up!!!