if u play postflop as good as mr Sulsky u can open wider than u do now :)

50% is already wide and expoitable. No need to make it wider. It's definitely right at lower stakes and Zoom, becausr players overfold the BB.

At a midstakes+ regular table, I would not open more than 35%

Don´t forget the rake on the low limits. You need 67% for auto-profit, are players really folding that much BvB in position on the low(er) stakes? On Zoom it might actually be that players preselected the "check/fold" option ...

How should a defend 3bet range look when you open wide at lower stakes?
I mostly 4bet or fold v a 3bet but it is not enough.

What would a reasonable flat 3bet range look like as a default?
Against players who 3bet 10-15% blind vs blind I am not sure what to do with a lot of the small-mid pocket pairs and TJs~ hands.

What videos suggest you should open wider?? 50% seems way too wide vs. a good player in the bb.