Airless tyres are available at least from Tannus but they're not solid tubes. They're solid tyres. A tube is something that fits inside a clincher or tubular tyre. I can't imagine how fitting a solid tube would be possible. There are several armors but they are not tubes, they are armors that fit between the air-filled inner tube and the tyre.
You shouldn't use airless tyres, however, as on nearly any kind of road they have excessive rolling resistance, which makes you so slow it takes the enjoyment away from cycling.
About the only case where extra puncture protection helps is areas that have ice on the roads during some parts of the year, and also at the same time have flawed decisionmakers that think cyclists should use the same paths that pedestrians use.
Pedestrians would fall all the time on ice, because ordinary shoes don't have studs, so therefore they distribute a form of sharp gravel made from crushed rock on these paths. This sharp gravel can have thin and long pieces as long as 14mm. The reason this happens is that they use 6mm sieve to filter away the largest crushed fragments, but a 5mm x 5mm x 14mm fragment would be small enough to fit through that sieve, as the sieve only restricts the two smallest dimensions of gravel pieces, and not the largest dimension of gravel pieces. Also, the crushed rock makes the gravel extremely sharp.
The combination of wet paths from melting snow and sharp gravel fragments that may be as long as 14mm mean that you have more than one puncture per 100km if you use ordinary tyres. The water acts as a lubricant between tyre rubber and the gravel pieces. In this case, I understand that someone might want to have extra puncture protection. However, also if riding in this environment you benefit from studded tyres. There are no studded airless tyres available, but you can buy a very thick tyre armor from Tannus. It fits inside the studded tyre and the inner tube but you do need to use much smaller inner tube because the armor is so thick. It can be used with any tyre, including a studded tyre.
The armor successfully prevents sharp gravel from puncturing your tyres. It also has a very high rolling resistance and is a real pain to fit between the tube and tyre (so you want to fit it once to a secondary wheelset and leave it there, not changing it every season). You want to use this armor only during the times the sharp gravel is on the roads. Once it has been collected away from the roads, you should swap to a summer wheelset that has low rolling resistance (=thin) tyres and no armor.