DD-X and TMax/RS are nothing like Xtol, chemically or tonally.
is almost identical in performance to Xtol. It differs chemically in several ways, but it’s definitely worth trying.
There are a lot of ascorbate liquid developers you can make yourself from formulae online. I only ever saw one, the late John Black’s JB9, however, which used a buffered 'weak' alkali. Xtol gets a lot of its performance from ascorbate, but thinking you can mix anything, or put some vitamin c in Rodinal and have an acceptable Xtol substitute is just dreaming. Strong alkalis will activate the ascorbate, but the developer performance is very different to Xtol.