Use bold font for just the hat in math mode

Question

I am using the libertinus font which also has math support. But when I try to place a hat on variables in this font, it seems too "flimsy." How to make the hat appear thicker?

I tried renewing the \hat{} command to use a bold font, but it also changes the variable.

\let\oldhat\hat
\renewcommand{\hat}[1]{\mathbf{\oldhat{#1}}}

$\hat{\lambda}$     %% This is ok. \lambda does not become bold, and hat looks nice.
$\hat{p}$           %% This is not ok. It makes p also bold.

$\mathbf{\hat{p}}$  %% Ideally I want this to work as expected as well (it works now).

Is there some way to achieve what I want to do? I was thinking of some \ooalign magic but wasn't able to figure out how to do it.

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(Edit)

The question might've been a bit unclear, so here's some more clarification.
I also tried to do something using \ooalign, but it's not perfect. The following is the basic setup.

\usepackage[T1]{fontenc}
\usepackage{libertinus}

\let\oldhat\hat
\renewcommand{\hat}[1]{{\ooalign{\ensuremath{\mathbf{\oldhat{\phantom{#1}}}}\cr\ensuremath{#1}\cr}}}

$\oldhat{P}\quad$       %% The hat is too flimsy
$\hat{P}\quad$          %% This is ok.
$\hat{\mathbf{P}}\quad$ %% This also works!
$\mathbf{\hat{P}}\quad$ %% Does not work!! ooalign messes up mathbf

This gives the output below:

As you can see, there are two issues with this.
The first is that the centering is not proper.
I think this is because the \mathbf{\oldhat{\phantom{#1}}} part puts the variable in boldface, which messes up with the centering.
Another issue is that \mathbf{\hat{P}} does not work.
How does one solve these two issues?

Another thing I wasn't so sure about was why we need so much \ensuremath inside \ooalign. It does not work without those (gives some error). Isn't it already in math mode? Why do we need to use \ensuremath again? Does \ooalign put stuff in text mode automatically?

Answer 1

You want the middle form, with \bm just applied to \hat

\documentclass{book}
\usepackage{bm}

\begin{document}

$\hat{V}\quad \bm{\hat}{V}\quad \bm{\hat{V}}$

\end{document}