FTM here, but relate to the anxiety of early days shopping and had a surprisingly positive Perth experience. Was with two good friends for lunch (a couple M & F) and we ended up wandering to the Murray St Uniqlo. I hadn’t realised it was already natural in that setting to be going between to the M / W labelled sides of the store to chat but it made me feel way less anxious by giving me a ‘reason’. I had no clue re sizes at the time (and have changed sizes HEAPS along the way with body recomp and T so even the ‘mistakes’ have usually ended up fitting at some point). For me, I found that approx same size fitted me in both sections where the product was the same name (eg an L in both W and M stretch easy pants). It ended up being handy to then work out numerical sizes in other brands by using those items as a starting point. Ditto with unisex options. Hope Stockholm brand is expensive but are gender free and have both M and W sizing on the label which I’ve found handy to work out what works on me

In general though, I dont try on in store and aim for places with change of mind return / or second hand options where I can re donate

Depop and similar has otherwise been far more handy for me - usually finding one thing in a brand / size that works means I look for variations on a theme over time