How to convert bezier to lines

You can apply extension Modify path > Flatten Bezier. the Flatness parameter affect “the smaller parameter the more nodes and the better fit”. The numeric value unfortunately tells something exact only for those who have time to read the documentation and who understand Bezier Curve mathematics.

ADD: I must admit I do not know how Flatness exactly is calculated but there’s a comment which says something about it.

You have no control where flattening actually inserts nodes.

There can occur cases where miter joints at nodes look weird. Check smoother joint options in the Stroke Style dialog.

You can draw the wanted polyline with the Bezier tool (=the Pen). Deselect the original to avoid joining. Set all point snaps on. Then click along the path. If you have snaps on you meet the curve with every click.

This needed 5 clicks on the curve and one right click to accept the generated red polyline.