Indeed, I don't have WP status, and most people don't.
So my past access to the SYD QFi F lounge, had been by buying a tix, split the time between that and the EK lounge at SYD T1.
This was pre covid tho.
Those who do have that tier (WP/P1), and they fly int out of SYD T1 even in whY/Y/J/F will have access to the SYD QFi F lounge, but...
If you are SG or lower, you will be relegated to the SYD QFi J lounge next door, unless you have "friends with benefits".
That is why I mentioned, if you really want to see the SYD QFi F lounge, buying a tix to CHC in EK F aka quasi QFi F is the only way to get into the SYD QFi F lounge.
Even if a person followed what the OP writes about, if they are QF SG or lower, unless they are a guest of a WP/P1, they will only get the next door lower grade lounge.
Buying a cheap tix to DPS also will be relegated to the J lounge, as those services do not have a F cabin.
Friends with benefits, then, yes, the SYD QFi F lounge awaits, if flying whY/Y/J.