"Dual boot" - DietPi on microSD and I need to reboot to Android on eMMC

I have a T95-Max-Plus Android Box, with Android TV installed on internal eMMC, and DietPi installed on microSD Card (thanks to this tutorial: DietPi img for Amlogic S905x-s905x3 TVBOX)

Everything is fine, it boots to DietPi on microSD (which is what I want), but if I feel like watching Android TV I need to power down, remove the microSD, then power on, and only then it boots do eMMC (Android TV) because the boot priority is microSD first but since it’s no longer there it boots to eMMC.

So what I really would like to have in DietPi is some sort of way to reboot to eMMC from microSD like CoreELEC has.
CoreELEC has an menu button option to “rebootfromnand” and as we can see here (Command to reboot to eMMC NAND to use on other skins? - #2 by bubblegum57 - Installation & Booting - CoreELEC Forums) it calls

/usr/sbin/rebootfromnand

Well, rebootfromnand is just an executable bash script that calls

#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2016-2018 kszaq (kszaquitto@gmail.com)
# Copyright (C) 2019-present Team CoreELEC (https://coreelec.org)
if /usr/sbin/fw_printenv whereToBootFrom > /dev/null 2>&1; then /usr/sbin/fw_setenv whereToBootFrom internal; fi
/usr/sbin/fw_setenv bootfromnand 1

So commands fw_printenv and fw_setenv are aparently part of u-boot-tools package (I have it installed) but I couldn’t find them, so I can not replicate this on DietPi…

I’m looking for a way to reboot to eMMC from microSD without having to physically remove the card, this would allow me to comfortable switch between the 2 operative systems, can anyone please tell me how to do it?

P.S: I’ve also tried to manually copied rebootfromnand, fw_printenv, and fw_setenv to /usr/sbin/ but the system can not execute them (I know it was dumb of me, but I was desperate).