[Redmi Note 9 Pro (International Model) General and] kheno:
This is good news from the rom developers, to know that they would be able to quite easily adapt their versions to work on the joyeuse version.

Though I think that this way you fake all software,... to believe the phone is another version.

Which could conflict in the future.

I would rather try the following:

Start from a joyeuse rom (with correct firmware, vendor, ... data)

And only copy/overwrite the required partitions (data/system/....) with those of a curtana rom.

So keeping the correct firmware, vendor, ...

That would leave you only to adapt the build.prop file to set model, ... (check with the joyeuese rom)

Just a thought, I have not much knowledge here.

But also trying to learn and try.

Would someone be able to explain me the partition layout and where to find the system?

I am confused not to find the system partition.

How do I for example also remount the system partition on these phones to make it writable?

adb shell "su -c 'mount -o rw,remount /system'"

I'm trying to understand how this works, sorry for being noob.

C:\Users\kheno>adb shell

joyeuse:/ $ su

joyeuse:/ # ls /dev/block

bootdevice loop1 loop4 ram1 ram4 sda11 sda3 sdb2 sde1 sde18 sde26 sde34 sde42 sde50 sde9

by-name loop10 loop5 ram10 ram5 sda12 sda4 sdc sde10 sde19 sde27 sde35 sde43 sde51 sdf

dm-0 loop11 loop6 ram11 ram6 sda13 sda5 sdc1 sde11 sde2 sde28 sde36 sde44 sde52 sdf1

dm-1 loop12 loop7 ram12 ram7 sda14 sda6 sdc2 sde12 sde20 sde29 sde37 sde45 sde53 sdf2

dm-2 loop13 loop8 ram13 ram8 sda15 sda7 sdd sde13 sde21 sde3 sde38 sde46 sde54 sdf3

dm-3 loop14 loop9 ram14 ram9 sda16 sda8 sdd1 sde14 sde22 sde30 sde39 sde47 sde55 sdf4

dm-4 loop15 mapper ram15 sda sda17 sda9 sdd2 sde15 sde23 sde31 sde4 sde48 sde6 sdf5

dm-5 loop2 platform ram2 sda1 sda18 sdb sdd3 sde16 sde24 sde32 sde40 sde49 sde7 vold

loop0 loop3 ram0 ram3 sda10 sda2 sdb1 sde sde17 sde25 sde33 sde41 sde5 sde8 zram0

joyeuse:/ # ls /dev/block/by-name/

ALIGN_TO_128K_1 catecontentfv devinfo hyp mdtpsecapp qupfw spunvm vbmeta_system

ALIGN_TO_128K_2 catefv dip hypbak mdtpsecappbak qupfwbak ssd vbmeta_systembak

abl cateloader dsp imagefv metadata recovery storsec vbmetabak

ablbak cdt dspbak imagefvbak minidump recoverybak super xbl

aop cmnlib dtbo keymaster misc sda toolsfv xbl_config

aopbak cmnlib64 dtbobak keymasterbak modem sdb tz xbl_configbak

apdp cmnlib64bak exaid keystore modembak sdc tzbak xblbak

bluetooth cmnlibbak ffu limits modemst1 sdd uefisecapp

bluetoothbak cust frp logdump modemst2 sde uefisecappbak

boot ddr fsc logfs multiimgoem sdf uefivarstore

bootbak devcfg fsg mdtp multiimgqti secdata userdata

cache devcfgbak gsort mdtpbak persist splash vbmeta

joyeuse:/ # df -h

Filesystem Size Used Avail Use% Mounted on

tmpfs 2.7G 1.0M 2.7G 1% /dev

tmpfs 2.7G 0 2.7G 0% /mnt

tmpfs 2.7G 0 2.7G 0% /apex

/dev/block/sda12 11M 72K 11M 1% /metadata

tmpfs 2.7G 6.3M 2.7G 1% /sbin

/sbin/.magisk/block/system_root 2.2G 2.2G 7.2M 100% /sbin/.magisk/mirror/system_root

none 2.7G 0 2.7G 0% /sys/fs/cgroup

/dev/block/sda13 344M 940K 343M 1% /cache

/dev/block/sde4 256M 127M 128M 50% /vendor/firmware_mnt

/dev/block/sde9 27M 20M 7.3M 74% /vendor/dsp

/dev/block/sda2 27M 1.3M 26M 6% /mnt/vendor/persist

/dev/block/sde5 64M 848K 63M 2% /vendor/bt_firmware

/dev/block/sda7 976M 914M 62M 94% /cust

/dev/block/loop2 836K 808K 28K 97% /apex/com.android.tzdata@292500001

/dev/block/loop3 5.2M 5.2M 32K 100% /apex/com.android.media@292000301

/dev/block/loop4 1.6M 1.6M 28K 99% /apex/com.android.resolv@290000000

/dev/block/loop5 5.0M 5.0M 32K 100% /apex/com.android.conscrypt@290000000

/dev/block/loop6 96M 96M 36K 100% /apex/com.android.runtime@1

/dev/block/loop7 232K 36K 196K 16% /apex/com.android.apex.cts.shim@1

/dev/block/loop8 21M 21M 32K 100% /apex/com.android.media.swcodec@292200001

/sbin/.magisk/block/product 1.0G 1.0G 3.3M 100% /sbin/.magisk/mirror/product

/sbin/.magisk/block/vendor 1.1G 1.1G 3.8M 100% /sbin/.magisk/mirror/vendor

/sbin/.magisk/block/data 105G 6.7G 98G 7% /sbin/.magisk/mirror/data

/data/media 105G 6.7G 98G 7% /mnt/runtime/default/emulated

Have no clue, still noob when it comes to these things