com.android.bluetooth - Core of Bluetooth services.
com.android.bluetoothmidiservice - Provides classes for sending and receiving messages using the MIDI event protocol over Bluetooth LE.
com.android.calculator2 - Stock calculator app.
com.android.calendar - Stock calendar app.
com.android.captiveportallogin - This consists in a web page that the user of a public access network is obliged to view and interect with, before access is granted. Like public Wi-Fi hotspots that prompts you with an user and password login.
com.android.carrierconfig - Provides access to telephony configuration values that are carrier-specific.
com.android.cellbroadcastreceiver - Alerts for Broadcasts.
com.android.certinstaller - Certificate installer. When removed, the Wi-Fi wouldn't be able to be turned on. DO NOT remove this.
com.android.companiondevicemanager - Companion Device Manager that comes by default in every Oreo+ device. This handles connections to other devices, like Bluetooth Headphones, desktop Operative Systems, ecc. DO NOT remove this.
com.android.contacts - Stock contacts app.
com.android.cts.priv.ctsshim - Compatibilty Test Service. Used to certify your device as "valid" or not. DO NOT remove this.
com.android.defcontainer - Needed for installer by applications.
com.android.deskclock - Clock app, plus alarm function.
com.android.dreams.basic - Support for screensaver mode.
com.android.emergency - Emergency Contacts. Remove it if you don't use this feature.
com.android.exchange - Needed for email app to work correctly if you use a mail different from Gmail.
com.android.facelock - Essential if you wanna use Face Unlock features, removable if you don't want to.
com.android.gallery3d - Gallery app.
com.android.htmlviewer - In-built HTML viewer.
com.android.hotwordenrollment.okgoogle - "OK Google" detection service (used when you wanna enroll Assistant by the hotword.
com.android.incallui - In Call User Interface - Controls various activities during a call.
com.android.inputdevices - Manages the input devices.
com.android.inputmethod.latin - AOSP keyboard. Safe to remove.
com.android.keychain - Should provide access to private keys plus their certificate chains in storage.
com.android.location.fused - NEVER REMOVE this. Provides everything you need for GPS, Cellular and Wi-Fi networks location data.
com.android.magicsmoke - Live wallpaper.
com.android.managedprovisioning - For corporate restritctions on phones with Google Workplace.
com.android.mediacenter - EMUI music app.
com.android.mms - Stock SMS app.
com.android.mms.service - Provides support for sending MMS messages with photos, videos, ecc.
com.android.nfc - NFC service. If disabled, Settings app could crash or not work.
com.android.noisefield - Live wallpaper.
com.android.phasebeam - Wallpaper.
com.android.printservice.reccomendation - Keep it, if you need to print directly via your phone.
com.android.pacprocessor - PAC stands for proxy auto-config, and this file defines how web browsers and other agents can automatically define the correct proxy server for fetching an URL. Removable, if you don't use proxies on your phone.
com.android.spul - SUPL20SERVICES, seems related to GPS in Huawei devices. Should be safe to remove.
com.android.systemui - System User Interface. DO NOT remove this.
com.android.stk - SIM toolkit app.
com.android.storagemanger - Storage Manager function, the one that details your occupied space on internal/external memory card and allows to see how many space is occupied by apps divided by sections, to be clear. DO NOT remove this.
com.android.traceur - Android stock developer tool included by default in every Pie+ device. Allows to locally save logs. DO NOT remove this.
com.android.vending - Google Play Store app.
com.android.voicedialer - Voice search.
com.android.vpndialogs - VPN system.
com.android.wallpaper.holospiral - Live wallpaper.
Obviously all bloatware apps and services related , Snapchat... etc.
com.amazon.aa - Amazon Assistant app.
com.amazon.aa.attribution - Amazon Assistant related package.
com.booking - Booking.com app.
com.ebay.mobile - eBay app.
com.facebook.appmanager - Facebook related stuff. Purge this.
com.facebook.system - Facebook related stuff. Purge this.
com.facebook.orca - Facebook related stuff. Purge this.
com.facebook.katana -Facebook related stuff. Purge this.
com.facebook.services - Facebook related stuff. Purge this.
com.instagram.android - Instagram app.
com.netflix.mediaclient - Netflix app.
com.netflix.partner.activation - Netflix related package.
com.microsoft.translator - Microsoft Translate app. Safe to remove.
com.snapchat.android - Snapchat App.
com.swiftkey.swiftkeyconfigurator - SwiftKey factory settings. Safe to remove.
com.touchtype.swiftkey - SwiftKey board. Safe to remove.
com.twitter.android - Twitter app.
org.smsalliance.openmobileapi.service - SmartcardService. "The SmartCard API is a reference implementation of the SIMalliance Open Mobile API specification that enables Android applications to communicate with Secure Elements, e.g. SIM card, embedded Secure Elements, Mobile Security Card or others."