Sweeteners affect some people’s weight-loss, I’ve read it several times. (Only net carbs seem to matter to me so I look at total carbs.)
There is no such thing as truly zero carb bread, IMO but those stuff in the shops are surely not that. A tiny portion having less than 1g net carbs doesn’t make something zero carb.
They may be okay for someone or not. It’s up to everyone to eat these or not. I almost only buy ingredients since almost a decade, some condiments are exceptions (and almost anything can happen on some days, I don’t want to be a hypocrite) but it’s understandable not everyone is this strict.
I don’t even know what is keto-friendly. ANYTHING fits my keto if I can squeeze it into my (net) carb limit. Some items don’t worth it, others do. It’s individual. Some people have problems with gluten or oat fiber or some sugar alcohols… I have problem with the stuff not being homemade, they surely use too much unnecessarily stuff or not the right quality… Maybe you are fine with them all…
Increasing bodyweight may mean nothing, it’s normal for it to change, it takes more time to figure out if there is a correlation.
I don’t recommend them, I would make my own or rather eat some proper food or snack BUT if they keep you from eating something way worse, they may be the lesser evil for a while. I wouldn’t consider them good food for keto, I wouldn’t use them freely, often, in bigger amounts… But they may have their role, be smart with them. Carbs are sneaky and you health and well-being is important, it’s not all about weight…