How to Check and Change Current Active Slot on Android [Fastboot

I hoped I could find a phone that had an sd card slot and headphone jack but active on the screen, in the name of battery my Bluetooth connection buffers

It may not flash TWRP as there is no active slot not bootable) If it is a slotted device in Fastboot run the command: fastboot getvar

fastboot get active slot fast boot Raspberry Pi OS The latest release of Raspberry Pi OS is made to get the most from Raspberry Pi 5 The newest version of our operating system

fastboot_ error_ failed to identify current slot But I want without fastboot command My usecase is the bootloader need to check the currect active slot and set the proper suffix How can I do