I did research with my mariko console, and I realized that we need proper mariko_kek, mariko_bek, and sbk in keyslot to boot hos on mariko.
keyslots are 'write only', and we can easily write keys to keyslots using hekate bdk, so I just made keyslot validator/writer payload. (Based on Lockpick_RCM)
Usage
1. Fill `keyslot.keys` and put it in the sd card path `sd:/switch/keyslot.keys`
2. Boot to hekate and chainload keyslot_writer.bin
3. Select `Validate keyslots` to validate keyslot 0-13
4. Select `Write to keyslots` to write mariko_kek, mariko_bek from file to keyslot 12, 13
5. Select `Reboot to hekate` (Do not select `Power off`)
6. Try to boot Atmosphere
Anyone who has installed rp2040 to mariko can try this method