Several efforts are ongoing for the development of spherical gaseous time projection chamber detectors for the observation of rare phenomena such as weakly interacting massive particles or neutrino interactions. The proposed detector, thanks to its simplicity, low energy threshold and energy resolution, could be used to observe the $betabeta0 u$ process i.e. the neutrinoless double beta decay. In this work, a specific setup is presented for the measurement of $betabeta0 u$ on 50~kg of $^{136}$Xe. The different backgrounds are studied, demonstrating the possibility to reach a total background per year in the detector mass at the level of 2 events per year. The obtained results are competitive with the present generation of experiments and could represent the first step of a more ambitious roadmap including the $betabeta0 u$ search with different gases with the same detector and therefore the same background sources. The constraints in terms of detector constructions and material purity are also addressed, showing that none of them represents a show stopper for the proposed experimental setup.
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