Seems to be useless, the state of art for all categories is local on-device, voice model vendors are just rent seekers for those who know no better.
You're not the customer. This is for people building products that support thousands of users.
Linux on desktop is great for you, but this is a tool for people delivering solutions.
Just canceled my WisprFlow subscription a few days ago to switch to a open source, free, local alternative. In my case handy.computer with the Cohere model.
Open weight models are getting really good. Specko appears to be focussing on paid services which has its role to play but I have a benchmark in development for Open Weight models here if that is helpful: https://orcabot.com/benchmarks/open-weight-tts.
Still shoring up the details but you can try a sample of all the options and see how they compare in terms of model size, peak RSS, real time factor etc.