@RJKD
I am a believer in keeping things simple.
For a logo such as TOTP which has plenty of straight lines - make all the straights as separate paths. Then if things go wrong, easy to delete one small part.
Some things to remember - a path has a start and an end (even if joined) but not a "T" junction. So 'butt' straights up where necessary but be careful with overlapping.
Edit paths -
ctrl-click adds nodes
shift-ctrl-click deletes nodes and paths between nodes.
Need a single combined path. Right click in the paths dialog and use combine visible paths.
A less than wonderful demo of the above.
https://youtu.be/SBnDjdmSjtQ A little too long, 5 and a half minutes.