I don't think that your phone is bricked. A bricked device doesn't usually boot at all, or is stuck in a bootloop. It might be a case of potentially corrupt zip. Here are the things that you can try before giving up on your Poco:
- Check if ADB detects your phone.
- Try booting into recovery (either from ADB, or using physical buttons); if you succeed, perform a clean flash of the ROM.
- If nothing works for you, try booting into fastboot and flash a stock MIUI fastboot ROM (from here) using Mi Flashtool.
if you're able to get into recovery mode then you'll be able to reset your device (if you're fine with losing your data). to do that, shut off your phone and hold power and volume up keys at the same time until you see the xiaomi or poco logo. once you're there, there will be an option to wipe data or reset. if resetting doesn't work, you can connect to ADB using a computer, and i assume if you have pixel experience installed you already have twrp or another custom recovery that lets you flash zip files, so you can either reflash or flash a different rom. good luck!