The heterotic G$_2$ system with reducible characteristic holonomy

We construct solutions to the heterotic G$_2$ system on almost contact metric manifolds with reduced characteristic holonomy. We focus on $3$-$(\alpha,\delta)$-Sasaki manifolds and $(\alpha,\delta)$-Sasaki manifolds, the latter being a convenient reformulation of spin $\eta$-Einstein $\alpha$-Sasaki manifolds. Investigating a $1$-parameter family of G$_2$-connections on the tangent bundle, we obtain several approximate solutions as well as one new class of exact solutions on degenerate $3$-$(\alpha,\delta)$-Sasaki manifolds.