Most definitely the tank, once cycled and making sure it’s heated, would be fine for the Betta. HOWEVER, it would need to be densely planted with tall plants, there should not be a strong current at all as fancy Bettas are not strong swimmers and any tank mates should be very docile, slow swimming and not brightly coloured, such as Corydoras.

In a cold unfiltered bowl the Betta would be more susceptible to parasites and infections as it’s immune system would be low due to extreme stress from the fluctuating temperatures and ever changing environment as you’d have to do large water changes several times a week.

If you live somewhere warm or ALWAYS keep your house warm you wouldn’t need a heater. These are tropical fish (from Thailand) so need a temperature of 20 celsius otherwise they won’t live long.

They are members of a group of fish called anabantids (like gouramies). These fish can breathe atmospheric air as well as dissolved oxygen through their gills so don’t need a proper aquarium with a large surface area for oxygen to enter although it seems a bit cruel to keep them in a bowl.