How to make 'adb shell' to read /etc/profile or other configuration files?

I am working on an embedded Linux system (kernel-5.10.24), and it uses ash from busybox as /bin/sh. The system support login from serial console and adb shell from PC. Now I found the shell started from serial console did read the environments defined in /etc/profile, but the shell started by adb shell does NOT. For example, the /etc/profile is as follows,

# cat /etc/profile
export PATH="/bin:/sbin:/usr/bin:/usr/sbin"

if [ "$PS1" ]; then
        if [ "id -u" -eq 0 ]; then
                export PS1='# '
        else
                export PS1='$ '
        fi
fi

in serial console,

# echo $HOME
/root
# echo $ENV

# echo $PATH
/bin:/sbin:/usr/bin:/usr/sbin

But in adb shell,

/sys/kernel/config/usb_gadget # echo $PATH
/sbin:/usr/sbin:/bin:/usr/bin
/sys/kernel/config/usb_gadget # echo $HOME
/

The shell started by adb shell is launched by adbd in target Linux, so is there a way to make the shell started by adb shell to read /etc/profile or other configuration files for its environments?