I use one 6' x 1/4" Master cable through the frame hole, to lock the bike frame to tall poles or electrical conduits or gas pipes. Cable is harder to cut than solid steel, requires a special tool. bolt cutters and battery grinders have problems with cable. I use a heavy master key lock. The round locks are particularly difficult to cut off, one has to cut the shaft twice. I cut one that wore out on my garage. I park everywhere, good neighborhoods or bad, still have everything. The cable also fits through my bike helmet sitting in a bag on the rear rack, which has a chin guard and cost $190.
As far as quick releases, I saw two "bikes" chained up missing front wheels and seats the day after Ky Derby last year. So I got rid of my quick releases. I don't think thieves are using or selling the parts, I think they are ditching them in the nearest alley for meanness. So they can both steal and litter. The Sunday after Derby last year my bike wasn't missing parts but the tire was punctured while I was in church. I had to push the bike home 6 miles but it was only an $8 problem. I usually carry a bike pump but I had left it in the garage for venturing out on this day of high crime incidence.
To replace the quick release on the front wheel I used a 10-32x5" steel screw with washers and elastic stop nut.
https://www.mcmaster.com/#90276A850 The nut is
https://www.mcmaster.com/#90715A115 Takes a screwdriver and wrench to get that off. Needs washers at the end to cover the frame. It comes in a pack of 50 so I have converted four bikes with that so far.
On the quick release seat, I used a 6 mm x 45 mm allen head screw and nut. Takes an allen wrench and crescent wrench to get that off. Because my bike has a cam under the quick release head, I had to grind down a 5/16"nc nut to that profile on one side to fit under the screw head. If using power tools, wear safety glasses.
I carry those tools on the bike to deal with flats out 30 miles from home, but leave the tool box at home when going to high crime neighborhoods. I wish I was strong enough to lift the bike on the bus rack as there is always a bus back from high crime neighborhoods, but I'm not. Bus fare is only $1.75 but transfers and waiting for the next one are so slow I prefer to ride the bike, on trips under 15 miles.
As far as a powered hub, getting all that mechanism off is such that a **** only a rare thief would take that much time. If a thief has a van and an acetelyne torch he can have my bike in 2 minutes, but that is an expensive setup and would likely get photographed by a passer by. There are gangs stealing scooters in my town, but nobody knows what an electric bike is in this town, so resale value would be very low. Nobody is selling electric bikes any closer than the state university town. I've never seen another electric bike in this town or in Louisville either.