Turn \mathbb characters bold in math mode

Here I place three copies in close horizontal proximity by defining \fakebold{}. One can obviously modify it to use more copies, or to apply vertical offset as well. The horizontal offset is given by \bshft, currently set to 0.18pt.

By using the \ThisStyle{...\SavedStyle...} feature of scalerel, it should work across math styles, so that $\fakebold{A_b} A_{\fakebold{b}} A_b$ will give the expected result.

\documentclass{article}
\usepackage{amsmath} % some math-related packages, not sure which of them are necessary
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{bm} % for \bm
\usepackage{fixmath} % for \mathbold
\usepackage{scalerel}
\newlength\bshft
\bshft=.18pt\relax
\def\fakebold#1{\ThisStyle{\ooalign{$\SavedStyle#1$\cr%
  \kern-\bshft$\SavedStyle#1$\cr%
  \kern\bshft$\SavedStyle#1$}}}
\begin{document}
\section{Some text $\mathbb{ABC}abc\cosh\div+\alpha$ some text} %1
\section{Some text $\boldsymbol{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %2
\section{Some text $\mathbf{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %3
\section{Some text $\pmb{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %4
\section{Some text $\boldmath{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %5
\section{Some text $\bm{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %6
\section{Some text $\mathbold{\mathbb{ABC}abc\cosh\div+\alpha}$ some text} %7
What comes next is new
\section{Some text $\protect\fakebold{\mathbb{ABC}abc\cosh\div+\alpha}$ some text}%8
\LARGE$\fakebold{\mathbb{ABC}a}\mathbb{ABC}a$
\end{document}

and a close-up: