If I were the bad guy, I would use the heavy duty cable cutter to cut your electronics into two piece along with the Li-ion battery. Then cut the cable and be on my merry way in less than 30 seconds.
You need to think like a bad guy to understand what he is going to do.
Or they would deep freeze using a portable canister of Freon or CO2. Battery stops working if its frozen.
There was a video on youtube where the guy was "stealing" his own bike in some big city. He showed up with a portable angle grinder that spits out huge amount of spark, makes noise like you won't believe and proceeded to spend about 5 minutes cutting away the heavy chain. No one bothered to stop him. Some even offered their condolence that the bike couldn't be freed.
Alarms are useless on cars and on bikes.
Best defense is to make yours less attractive to a thief. As the old saying goes, "when backpacking, I just need to outrun my friend if we get chased by a grizzly"