sheet metal bending aluminium 1

i'm an amateur maker meddling with diy electronics etc. i've been wanting to make my own cases and i'm thinking about using aluminum sheet metals for that purpose.

google searches leads me to things like bending allowance and K values
however, bending allowance and K values say nothing about the minimum internal bending radius smaller than which the material/metal/sheet would simply break rather than simply yield and bend

lets assume that i prefer to use aluminum sheets (i'm not sure about grade but lets say grade 300x, on the notion of the most common)
some of those bending tables i stumbled into with google searches includes

lets say i prefer to use 0.8mm - 1mm sheets (31 mils - 39 mils)
base on the tables found above, i'm getting 0 (zero) or none (blank not specified) for those sheets 0.8mm - 1mm

now my question is:
do 0 (zero) or none (blank not specified) for 0.8mm - 1mm thickness aluminium sheets means that there is no minimim bending radius I can simply hem it without leaving any radius.

or do 0 (zero) or none (blank not specified) means that 0.8 - 1mm aluminium sheets cannot be bent?

thanks much in advance !
p.s. i won't be using a sheet metal brake, i'm using the most primitive tools of them all, possibly angle bars and a mallet / hammer