I highly doubt that hydrogen heating was ever considered. It's usually pushed by the gas lobby (since most hydrogen comes from gas), and Sweden doesn't have a strong gas lobby.
Most of the current energy production in Sweden was built starting 50 years ago, which can be seen in the graph. Since the early 1990s the combination of hydro power and nuclear has had an almost static production rate, and hydro power in particular has been maxed out. Oil was and is still used as the reserve energy, through new plants currently being built are based on natural gas rather than oil. The political statement is that the goal is that bio fuels should be used, but that the mix will be based on the market and the economical viability of different compatible fuels.
https://ourworldindata.org/grapher/energy-consumption-by-sou...
I highly doubt that hydrogen heating was ever considered. It's usually pushed by the gas lobby (since most hydrogen comes from gas), and Sweden doesn't have a strong gas lobby.