Hello,
Theme Options > General > Enable Old Widgets Panel, then go to Appearance > Widgets > add widgets into Shop page sidebar. If this is not what you are looking for, please describe your request in more detail.
I can see a problem on your Shop page, enable debug mode in WordPress – https://wordpress.org/support/article/debugging-in-wordpress/ to find out what error appears on your site, it will point you in the right direction what needs to be fixed.
Regards
