Here's the same treatment for the first six steps of the famously unruly r pentomino

There's other variations that might be more visually interesting (or at least more varied: what if instead of doing a strict convex hull you did a sort of shrinkwrap maneuver (there is probably a good bit of math jargon for this but I have no idea) such that pieces like the fifth step of the r-pentomino looked like this instead?

(Though i'm being very loose and sketchy and don't feel like I've defined a remotely consistent ruleset in my head for that last variations; why would the fifth step "U" piece shrink into the cavity like that but the second step piece wouldn't? For that matter, why wouldn't ALL the diagonal sink into tight corners? At which point instead of having any diagonals at all it'd just have flood-filled versions of the original pieces with steps 3, 4, and 6 no longer having empty cavities in the middle)

Another possible variation: convex hull but then also carve out any fully-encolosed cavities within that outer hull, like so. Though that's a little aesthetically jarring: why are we taking diagonal approaches to the exterior but returning to sharp blocky interiors?

Perhaps more consistent: for those interior cavities, take the convex hull of the perimeter of the cavity itself too. This doesn't change steps 3 and 4 of the r, but for 6 we get this new diagonal that feels more in the spirit of the thing.