No pressure cooker? I would still get a real light then leds super week and batteries are going to die in the middle of grow.
A pressure cooker is unnecessary, and these days in the USA you have to, in most places, sign a sheet with lots of identifying information to even purchase one. Steaming glass jars in a large pot with a tight-fitting lid is all that is necessary, provided that you steam it for long enough.These LEDs are daylight wavelength, so they are not "weak". Also, in a dark large room, at night, this sucker lights up the large room nicely enough for me to see well. That's more than enough for the shrooms. Mushrooms only NEED a very, very small amount of light to stimulate pinning in the proper direction and they only really NEED a few MINUTES a day of this. I also have a brighter LED clamp lamp and an extension cord that I plan to run into the closet, as my computer desk with all the cables is right next to the closet in my office. Nobody would notice it.
my best suggestion is to go to shroomery.org and read read read before doing anything.