Have you looked at Lektor? https://www.getlektor.com/ https://www.getlektor.com/ . We use it for in-house needs and we have also built an extension, Lektorium h

Have you looked at Lektor? https://www.getlektor.com/ https://www.getlektor.com/ . We use it for in-house needs and we have also built an extension, Lektorium https://github.com/sphericalpm/lektorium https://github.com/sphericalpm/lektorium that allows us to create hosted instances of Lektor for content managers who aren't technical enough to run Lektor locally.