Businesses seeing a drop in revenue as a result of a random patchwork organized online effort for a temporary boycott won’t have any effect?
No it won’t. This just means people buy the stuff the another day and is absolutely meaningless to their bottom line
I spent most of my 20s doing grassroots campaigning, with a large part of it being protest planning and organization. You generally do not need a permit to conduct protests on public property, even large ones, in the USA.
The exceptions are very specific; i.e. blocking roads may require a permit.
https://www.aclu.org/know-your-rights/protesters-rights