Thank you jcl. I can confirm this dll solves this problem. Much appreciated.

It does work with curl. HTTP redirects need to be followed. curl -L

curl -v -H "Content-Type: application/json" -H "Authorization: Bearer DummyAPIKey" "https://api-fxpractice.oanda.com/v3/accounts"
Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x55746ec5d800)
GET /v3/accounts HTTP/2
Host: api-fxpractice.oanda.com
user-agent: curl/7.68.0
accept: /
content-type: application/json
curl -v -H "Content-Type: application/json" -H "Authorization: Bearer DummyAPIKey" ""https://api-fxpractice.oanda.com/v3/users/@/accounts"
{"accounts":[{"id":"101-001-FAKENUMBER-001","tags":[]}]}
curl -L -H "Content-Type: application/json" -H "Authorization: Bearer DummyAPIKey" "https://api-fxpractice.oanda.com/v3/accounts"
{"accounts":[{"id":"101-001-FAKENUMBER-001","tags":[]}]}