yeah, i just plugged the nvme after install to my linux pc with a nvme to usb
then i copied the efi folder from mininstall img and the dtb file to the partition that appears in file manager 
and finally i can boot from nvme <3
load nvme 0:1 ${fdt_addr_r} jh7110-starfive-visionfive-2-v1.2a.dtb
load nvme 0:1 ${kernel_addr_r} efi/boot/bootriscv64.efi
bootefi ${kernel_addr_r} ${fdt_addr_r}
or automatic like in youre post:
env default -a -f
setenv distro_boot_env “echo Booting OpenBSD from NVME; load nvme 0:1 ${fdt_addr_r} jh7110-starfive-visionfive-2-v1.2a.dtb; load nvme 0:1 ${kernel_addr_r} efi/boot/bootriscv64.efi; bootefi ${kernel_addr_r} ${fdt_addr_r}”
saveenv
reset
thank you <33