Power outputs 5v and arduino with powerbank

Hi guys,
I wanted help with a simple project that I'm doing. I don't have much knowledge of electronics, but I wanted an arduino to control a siren and a led strip, both of 5v.
The arduino and power supply must be enclosed in a waterproof case. I was thinking about feeding the arduino with a powerbank (I analyzed a model with dimensions that interest me and with a capacity of 5200mah).
Will I be able to use the powerbank as I mentioned? Can I feed the outputs and feed the Arduino, and allow control of the outputs using NPN transistors?
I already found waterproof led tape (1 meter with 30 leds, which consumes 18W), but what buzzer or siren can I use with good volume, that I can feed with the powerbank?
I would love to hear your help and ideas ... I intend it to be something simple and practical, due to the little knowledge I have
Thanks :smiley:

If your case has any wires to the outside, it is water RESISTANT, but not WATERPROOF.
Are you looking for a mechanical siren or electronic siren? You can get "buzzers" with almost any level of sound you want. Use the search capability of some of the electronic distributors.
Use MOSFETS for control, not NPN transistors. They waste too much power in heat.

You may find that you have to deliberately draw additional current from the powerbank as some of them will shut down if the current draw is less than a certain threshold (which probably varies between manufacturers). You should try it and see with the powerbank you intend to use. I've got 1 or 2 really cheap powerbanks and they put out 5v continuously with an Arduino UNO clone connected. It's wasteful on the power but ok for a quick and dirty field lashup.