JDK 11+ Kotlin + TornadoFX (+ JavaFX) + GraalVM build file (Windows: DLLs you probably need in the same directory as the exe file: https://drive.google.com/file/d/1heqtORvUaIfshxQ59Dhp-fBiziF_WPHK/view?usp=sharing)

graalvm_pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>tornadofx-maven-project</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>

    <properties>
        <kotlin.version>1.5.10</kotlin.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>no.tornado</groupId>
            <artifactId>tornadofx</artifactId>
            <version>1.7.20</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-test</artifactId>
            <version>${kotlin.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-controls</artifactId>
            <version>15.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-graphics</artifactId>
            <version>15.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-media</artifactId>
            <version>15.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-web</artifactId>
            <version>15.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.framework</artifactId>
            <version>1.10.0</version>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-base</artifactId>
            <version>15.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-fxml</artifactId>
            <version>15.0.1</version>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>src/main/kotlin</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <release>11</release>
                </configuration>
            </plugin>
            <plugin>
                <groupId>com.gluonhq</groupId>
                <artifactId>client-maven-plugin</artifactId>
                <version>0.1.39</version>
                <configuration>
                    <mainClass><!--your main class--></mainClass>
                    <reflectionList>
                        <!-- Enter here every class you made just to make sure e.g: -->
                        <list>com.example.demo.app.MyApp</list>
                    </reflectionList>
                    <nativeImageArgs>
                        <list>-H:+AllowIncompleteClasspath</list>
                        <list>--no-fallback</list>
                        <list>-H:IncludeResourceBundles=tornadofx/i18n/ViewModel</list>
                        <list>-H:IncludeResourceBundles=tornadofx/i18n/Wizard</list>
                    </nativeImageArgs>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.openjfx</groupId>
                <artifactId>javafx-maven-plugin</artifactId>
                <version>0.0.4</version>
                <configuration>
                    <mainClass><!--your main class--></mainClass>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                        <configuration>
                        <jvmTarget>11</jvmTarget>
                        </configuration>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>