Low cost option without IPv4, over Hurricane Electric tunnel.

Shared IPv4 only. Cheap option to test IPv6 services.

IPv6 only VPS - Free Tier 1 vCPU / 512MiB

VPS with 1 vCPU, 512 MiB of RAM, 8 GiB of storage and 500GiB of traffic.
Network limited to 2 Mbps.
Use "freetrial" coupon and select yearly billing to get your free trial.
Uses HE IPv6 tunnel.

IPv6 only VPS - 1 vCPU / 1GiB

VPS with 1 vCPU, 1 GiB of RAM, 40 GiB of storage and 500GiB of traffic.
Uses HE tunnel for IPv6.

IPv6 only VPS - 2 vCPU / 2GiB

VPS with 2 vCPU, 2 GiB of RAM, 40 GiB of storage and 800GiB of traffic.
Uses HE tunnel for IPv6.