I'm a longtime user of Open Shell (formerly Classic Shell). Open/Classic Shell implement legacy start menu emulators all the way back to NT4/W2K (still my personal preference), but taskbar positioning is not and never was a feature of Open/Classic Shell.
To position the taskbar vertically under Win11, we need an additional 3rd-party tool. Explorer Patcher (also OSS) has done this trick for me and so far integrates smoothly with Classic Shell. With this, I got my familiar taskbar/start menu setup back. Nonetheless, I wish I could get this self-evident feature natively from Microsoft without having to use "hacks".