siunitx - bold decimal separator

Question

In this mwe, the first décimal separator is not bold, how to fix this?

\documentclass{article}
\usepackage{siunitx}

\sisetup{
    unit-mode = text,
    locale=FR,
    detect-all,
    inter-unit-product = \ensuremath{{}\cdot{}},
    group-minimum-digits=4,
    text-angstrom={Å},math-angstrom={\text{Å}},
    text-micro=\ensuremath{\othermu},
    math-micro=\othermu,
}

\begin{document}

$\num[math-rm=\mathbf]{.1}$ \textbf{0,1} \textbf{\SI{.1}{\km}}

\end{document}

Answer 1

The following MWE demonstrates that \mathbf itself does also not yield a bold comma. You could alternatively use \bm from the eponymous package:

\documentclass{article}
\usepackage{siunitx}
\usepackage{bm}

\sisetup{
    unit-mode = text,
    locale=FR,
    detect-all,
    inter-unit-product = \ensuremath{{}\cdot{}},
    group-minimum-digits=4,
    text-angstrom={Å},math-angstrom={\text{Å}},
    text-micro=\ensuremath{\othermu},
    math-micro=\othermu,
}

\begin{document}
$\num[math-rm=\mathbf, mode=math]{.1}$ \textbf{0,1} \textbf{\SI{.1}{\km}}

$\mathbf{,},$

$\num[math-rm=\bm]{.1}$ 
\end{document}

Answer 2

In math period and command are setup in a way that they don't react to mathbf. You could change this (be aware that this changes spacing and so font used by the chars. Depending on your real font setup it can have side effects):

\documentclass{article}
\usepackage{siunitx}
\sisetup{
    unit-mode = text,
    locale=FR,
    detect-all,
    inter-unit-product = \ensuremath{{}\cdot{}},
    group-minimum-digits=4,
    text-angstrom={Å},math-angstrom={\text{Å}},
    text-micro=\ensuremath{\othermu},
    math-micro=\othermu,
}
\DeclareMathSymbol{.}{\mathalpha}{operators}{"2E}
\DeclareMathSymbol{,}{\mathalpha}{operators}{"2C}
\begin{document}

$1.234\quad 1,234\quad  \mathbf{1.234\quad 1,234} \quad\num[math-rm=\mathbf]{.1}$ 

\end{document}

An alternative is to use a textfont: \num[math-rm=\textbf].