It looks like there are some serious investors involved that clearly believe that these guys know what they are doing. They presumably did their due diligence. That generally means this company used some seed funding to do proof of concepts and prototypes that are showing some promise.
In any case, 20M is nice but clearly nowhere near enough for mass producing stuff like this. So, what this means is this company just received funding to do more R&D from a nice consortium of investors that would clearly benefit from having a stake in a company like that if it had at all any chance of succeeding. Presumably there are still some hard problems left to work on otherwise, we'd be reading about some company investing billions to actually build the factories to mass produce this.
Since there are now several companies working on solid state batteries, the chances seem pretty good that one of them will eventually come up with viable products that can be produced at a quality, scale and cost that is interesting.
IMHO that will likely happen second half of the next decade or so. One application where this stuff might be applied early might be electric planes. That's a use case where improved energy density and safety is so valuable that even a very expensive solid state battery might still be interesting.