Extrude edges (or a curve) using an offset/inset to create a mitred patch of faces? [duplicate]

I'm trying to find a way to quickly use a curve or series of edges as an outline for creating a mitred patch of coplanar faces.

I guess what I'm actually asking is whether there's a way to draw a series of edges and then extrude them into faces, but... rather than extrude all of the new edges in the same direction, can they be extruded so that they each remain perpendicular to their respective original edges, creating a mitre where they meet, like what an offset or inset does?

Here's what I mean:

• (A) I start with a series of edges; then I want to...
• (B) offset those, like an extrusion inwards or outwards but specifically inwards in this case, so as to create new faces; and
• (C) Adjust the thickness later.

I will explain how I've already accomplished this, but I'm hoping someone can help me find a quicker way to do this.

1. Start with a single vertex, and extrude it to create the edges I want => this gives me (A).
2. Take that mesh and convert it to a curve (while using Keep Original, and setting the new curve to 2D)
3. Use Object Data > Geometry > Offset set to a negative value -- this creates the main effect of what I mean by offset/inset, because unlike (say) doing a scale, this method does what I'd call "a perpendicular projection" of each edge.
4. Convert that offset curve to a mesh again.
5. Join (CTRL+J) the two meshes, hence giving me now an outline for the outside and inside edges of the faces.
6. Connect the open ends of those two outlines and fill to create one big polygonal face.
7. Use the knife tool to cut the mitred corners between each pair of vertices.
8. Now I have (B).
9. Finally, I get to step (C) by selecting the inside edges and doing an Edge Slide (with Clamping disabled) to adjust the thickness both in and out as I need.

So, can anyone suggest how I might do this more quickly and easily?

Next, select the whole mesh and flatten it by scaling to 0 on the Z axis (S + Z + 0). This will leave some duplicate vertices (as the top and bottom faces are now "flattened" on top of each other). Select the whole mesh, and pick Mesh > Clean Up > Merge By Distance to clean it up.