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It is not possible: your condition $|f_n|<|f|$ implies that the zero set of $f_n$ is contained in the zero set of $f$. So $f(x)=|x|^{\alpha}$ cannot be approximated by a smooth function $f_n$, since $f_n(x)=(c+o(1))x$, and $\sup|f(x)-f_n(x)|\geq (1+o(x))|x|^\alpha$ for small $x$.