It seems that the official custom devices support in Flutter SDK is useful for us.

• Custom device types as a solution for custom embedder support for flutter run flutter/flutter#65067
• [flutter_tools] Add support for custom devices flutter/flutter#78113
• [custom devices] review & improve usability flutter/flutter#79406

Custom devices in Flutter SDK works fine.

$ flutter config --enable-custom-devices
$ touch ~/.flutter_custom_devices.json

~/.flutter_custom_devices.json which is an example I've tried with my localhost.

{
  "custom-devices": [
    {
      "id": "embedded-linux",
      "label": "Embedded Linux Device",
      "sdkNameAndVersion": "Target Embedded Linux Device",
      "disabled": false,
      "ping": [
        "ping",
        "-w",
        "500",
        "-c",
        "1",
        "localhost"
      ],
      "pingSuccessRegex": "ttl=",
      "postBuild": null,
      "install": [
        "scp",
        "-r",
        "${localPath}",
        "user@localhost:/tmp/${appName}"
      ],
      "uninstall": [
        "ssh",
        "user@localhost",
        "rm -rf \"/tmp/${appName}\""
      ],
      "runDebug": [
        "ssh",
        "user@localhost",
        "<path>/flutter-client -b /tmp/${appName}"
      ],
      "forwardPort": [
        "ssh",
        "-o",
        "ExitOnForwardFailure=yes",
        "-L",
        "127.0.0.1:${hostPort}:127.0.0.1:${devicePort}",
        "user@localhost"
      ],
      "forwardPortSuccessRegex": "Linux",
      "screenshot": [
        "ssh",
        "user@localhost",
        "fbgrab /tmp/screenshot.png && cat /tmp/screenshot.png | base64 | tr -d ' \\n\\t'"
      ]
    }
  ]
}

$ flutter devices
3 connected devices:

Linux (desktop)                • linux          • linux-x64      • Ubuntu 20.04.2 LTS 5.4.0-66-generic
Chrome (web)                   • chrome         • web-javascript • Google Chrome 89.0.4389.82
Embedded Linux Device (mobile) • embedded-linux • linux-arm64    • Target Embedded Linux Device

$ flutter run -d embedded-linux --verbose

At least now, I think flutter-tizen's approach is better than using custom devices in Flutter SDK. Because custom devices in Flutter SDK don't support building a custom embedder. However, if we develop Android apps, iOS apps, Linux desktop apps, and Embedded Linux at the same time, we need to use two tools... Also, Extension for VSCode is an issue.

For the time being, we will go with making a new tool like flutter-tizen.

If we create a custom tool / flutter tool fork, it will be a pretty big maintenance burden. So, I'll consider to add some options into Flutter SDK.

I'm creating a new tool for this embedder, which is flutter-tizen based. Also, I'm going to create a new repo.

I published flutter-elinux.

Would the fork of the flutter CLI tool that is maintained in flutter-elinux be deprecated if this PR flutter/flutter#90958 or something similar is merged? Or are there more differences in how the flutter-elinux fork functions compared to the official flutter CLI that would still be necessary even after that PR is merged?

I suspect you'd still need to maintain your fork.

Ok, that makes sense. Since commands like flutter-elinux build support flags such as --target-backend-type
and that downloading artifacts are retrieved from https://github.com/sony/flutter-embedded-linux/releases (or an alternative specified url by an environment variable ELINUX_ENGINE_BASE_URL )

Though it does appear that providing specifying artifact urls was considered for custom-devices flutter/flutter#79406 (comment)

I wonder if deprecating the fork is possible if custom-devices supported specifying artifact urls and something like the keys in the aformenetioned PR, namely configureNativeProject and buildNativeProject. Would those keys or something very similar supplant the custom flags like --target-backend-type?

I'm not sure what other issues are solved by the fork. Perhaps VSCode Extension mentioned above?

"Also, Extension for VSCode is an issue."