based on Links in mindmap as table of contents in beamer - If you do the yourself, you can build it in any way you like
\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{mindmap,trees,shadows}
% total number of sections %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{totcount}
\newcounter{totalsection}
\regtotcounter{totalsection}
\AtBeginDocument{%
\pretocmd{\section}{\refstepcounter{totalsection}}{}{}%
}%
% number of subsections per section %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{xcntperchap}
\RegisterCounters{section}{subsection}
\newcounter{totalsubsection}
\setcounter{totalsubsection}{0}
% creating automatic label %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% based on https://tex.stackexchange.com/a/386557/36296
\AtBeginSection[]{%
\label{sec:\thesection}
\begin{frame}
\frametitle{Outline}
\mindtoc
\end{frame}
}
\AtBeginSubsection[]{\label{subsec:\thesection:\thesubsection}}
\newcounter{currentsub}
\newcounter{totsection}
\newcommand{\mindtoc}{%
\centering%
{%
\usebeamerfont{section in toc}%
\usebeamercolor[fg]{section in toc}%
\setcounter{totsection}{\number\totvalue{totalsection}}%
\hyperlink{sec:\thesection}{\nameref{sec:\thesection}}%
\setcounter{currentsub}{\ObtainTrackedValueExp[\thesection]{section}{subsection}}%
\par%
}%
{%
\usebeamerfont{subsection in toc}%
\usebeamercolor[fg]{subsection in toc}%
\ifnum\thecurrentsub>0%
\foreach \j in {1,...,\thecurrentsub}{%
\hyperlink{subsec:\thesection:\j}{\nameref{subsec:\thesection:\j}}
}%
\fi%
}%
}
\title{Some Title}
\begin{document}
\section{Section One}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\subsection{Subsection}
\frame{}
\section{Section}
\frame{}
\section{Section}
\frame{}
\section{Section}
\frame{}
\section{Section}
\frame{}
\end{document}
