I can recommend the xiaomi phones. Had a bunch of them. Currently running the Mi11i. "Most" Xiaomi's have dual sim and expandable memory (you cant use 2 sims and mem card at the same time. ) I cant stand there OS MIUI - but I think coming from apple you'll like it. Admittedly I run the phones on Pixel OS (so its like a Google Pixel)
There naming conventions and model numbers are a bloody pain to work out ie Redmi, Redmi Note, Mi, Poco, K series, 12 series. Within each series you can have multiple models ie Mi 11, Mi11 Ultra , Mi11 light, Mi11 Pro and then some of these are 4G or 5G
Oppos in general I don't like due to their ColorOS - very restricted if you want to do some changes - it's been a couple of years since I tested one but I cant remember the exact problem but it was a simple home scrreen change and I couldnt even change the launcher (allows your phone to adjust the way you want it to look). This may have changed. The other issue is it contains a ton of bloatware. Xiaomi does to but at least youre able to remove it.
What ever phone you get you should look at 4gigROM - 6gig recommended for 2nd tier phones - the more apps you install and have running the slower it is.
Poco 4 is great for games whereas Mi series has a better camera.
Most 2nd tier phones unfortunately have no local support and typicallly buy from Bangood, Aliexpress .
I would stretch your dollar further if purchasing in Oz and get the OnePlus
HTH