RE: Use your .co.za domain with a VPS provider like Contabo or Hostinger.

I'm not too familiar with nginx(I use Caddy which support v6 out the box), but as long as it lists on [::1] you should be good to just add the record. According to google(https://www.google.com/intl/en/ipv6/statistics.html#tab=per-country-ipv6-adoption), only about 1.5% of South Africa supports v6, but with the recent changes like AWS charging for ALL IPv4 addresses, including those in use we are going to see that go up and up. Worldwide we are at about 45% v6 support, and the RIRs have ran out of v4 space to even give out. Buying a block of 256 IPv4 addresses costs about $8,500 right now(and it peaked at around $15k during 2022 I believe). It's worth it to support v6.