Strike is a Bitcoin only trading platform, run by a reputable dude (Jack Mallers)
Referee needs to join AND purchase some Bitcoin for both parties to qualify for the reward.
In my opinion, it's the best way to buy, sell, use and especially dollar cost average Bitcoin. It's simple to set up and the fees are low
"Strike is a platform that allows users to buy, sell, send, and receive bitcoin. Users can transact with Lightning Network payments using their debit cards or bank account, without the need for a wallet or previous Bitcoin experience".
I can vouch for Strike. In 2025 they will add AUD onramp according to the rep on r/strikebtc
You can set up recurring payments as little as $0.50 per hour and then when you reach a certain balance direct it to withdraw automatically so you don't create too many small UTOXs
I've been buying on Kraken Pro for my personal and SMSF accounts, then using free withdrawals via Lightning Network to Strike then using the low priority onchain withdrawal (takes about 12 hours).
App is great too.