That emoji is pretty versatile, from what I've seen it can resemble feeling melancholy, dead inside, exhausted, or a sarcastic "I'm fine". But as with most emoji's, it's all about context clues to fully understand why it was chosen.

After unlocking OEM, you need to go to samsung's dev website and sign in with a samsung account to find the instructions for unlocking the A25 bootloader. This usually just involves downloading a file to run on your computer with the phone plugged in, but some samsung phones have different steps depending on it's specific software version.

Once the bootloader is unlocked, reboot the phone into download mode by pressing Volume Down + Home + Power as soon as it restarts.

Next, download, install, and launch Odin. In Odin, select the AP tab and load the ROM of your choice, then flash the phone. After this is done, disconnect and reboot the phone. From here you should be good to go with the new OS on your A25.

They are quite different molecularly, Concerta is extended release methylphenidate (instant release is Ritalin) while Adderall is instant release dextroamphetamine and amphetamine. But there's also extended release Adderall too. All in all, it'll come down to your specific neurobiology regarding the best treatment option. However, if appetite suppression is a concern for you, using an instant release med will decrease the amount of time the med is active, which should reduce the duration of any appetite suppression.