I hear that some Amish sects permit the use of technology that's older and proven not to be too worldly, like washing machines, chainsaws, and Java 11. Have you considered converting?
Virtual threads only became stable in Java 21, unfortunately (https://openjdk.org/jeps/444). If the issue is "I'm bound to Java 8" proposing running a research build of Java 11 in production is going to fly as well as a lead balloon on the moon.