Just a quick how-to for anyone finding this thread, I installed DSM 7.2-64561 on my F2-220 quickly and all features work (except those that require a valid Synology account login as I do not have a valid Synology serial). I had a lot of trouble with a few different bootloader apps so figured I'd chime in with what finally worked
Remove the internal USB flash drive
Just for safety's sake and future use I made an image of the TOS internal flash drive using Passmark imageUSB (https://www.osforensics.com/tools/write-usb-images.html), I wrote the new image to another flash drive and tested it by booting the F2-220 successfully
Installed win32diskImager (https://sourceforge.net/projects/win32diskimager/) for writing the bootloader image(s) to new USB drives
Downloaded fork arpl-i18n fork version 23.5.10 (https://github.com/wjz304/arpl-i18n). I tried every single redpill loader related bootloader, fork, etc both the original and automated variety and each one failed for some reason or another EXCEPT this one.
Wrote arpl-i18n 23.5.10 to a new 32GB USB flash drive. (A note about flash drives: I spent a couple of hours banging my head against a wall trying to install this with other loaders and my initial problem was the USB flash drive it self. If you are having errors when trying to build try a different flash drive, preferably different brand/manufacturer. I had several Silicon Power drives that all had same errors when trying to build, had some issues with other drives too, this is apparently VERY sensitive about drive/speed/manuafacturer. The one that finally worked for me was a generic drive I happened to find in a drawer. Again, if you're struggling with errors in build, try a different flash drive).
Replaced the new arpl-i18n drive in my F2-220, plugged in the ethernet and power and booted up.
F2-220 will pull an IP address from DHCP, so after it has booted up, check your router or run your preferred network scanner to find its IP address
Installation can be down via browser or SSH, if using a browser goto http://<IPADDRESS>:7681
Go through the first 3 menu items
Model I choose 918+
Build 64561
Chose first MAC address
Autogenerate serial number
Auto select number of SATA ports
Build
It will take a few minutes to download and build the bootloader (depending on your internet connection)
After build is complete you'll be presented with the option to soft boot to the new DSM bootloader
Once it has loaded, point your browswer to http://<IPADDRESS>:5000 and follow instructions to install Synology DSM. I chose to upload and install the 7.2 build I had downloaded direct from Synology, but I could have chosen to auto-install and let it download the newest version as (at the time I'm writing this), the newest build was 64561, same as the newest build to download from Synology
Skip the account registration/login step as it will fail since you have a generated serial number that does not match any actual Synology device
Reboot and enjoy
Everything works except remote access type tools that rely on the Synology account login, etc
