RaspberryPi home NAS

I am looking for some solution to turn up my RPi3 to home NAS. I am running out of space in Google Photos so I would like to store my photos on my own drive. I was looking for some solution but I didn't found something good. My idea:

1. On RPi is running some system with my own HDD drive
2. That system have some settings where I can sleep that drive - e.g. during night so it doesn't make sound
3. I can access that storage through webapp which is on localhost
4. (optional) Store there not only photos and videos but also some files
5. That system has some android app which could sync my photos&videos to that NAS
6. (question) Could I access NAS from outside my home? I have read that is some solution to just edit something in Wifi router to access it from outside but idk if it is safe and even possible.

Thank you for answers, this topic is not very familiar with me so I am asking.

You're probably looking for something like OpenMediaVault:

https://www.openmediavault.org

I've used this on pi boards previously, though I've subsequently focused more on NFS and GlusterFS-based solutions I've built myself. Here's a three-node GlusterFS cluster that shows a few of the options for storage - those same options can be used for OMV.

For the storage devices you can use a USB to SATA cable with an HD (spinning disk will require external power, SSD generally won't), or use various USB solutions, like those shown here - regular USB keys or USB-NVMe. Make sure you use pi4 boards, which have USB-3 (the early models only had USB-2)

Good walkthrough here