Both of these things are true. Neither cancels the other.
The film career is easier to document and has been documented extensively. The invention is harder to explain and has been both understated and overstated in ways that have obscured what actually happened. The understated version — she was just an actress, the invention was a hobby, it never amounted to anything — is demonstrably wrong. The overstated version — she single-handedly invented Wi-Fi and was robbed of credit by a sexist military establishment — is a myth that serves emotional purposes but misrepresents the historical record.
The accurate version is more interesting than either myth. A woman who had grown up in one of Europe’s most cultured cities, had been married to an arms manufacturer whose dinner parties she listened to with the attention of someone who wanted to understand, had escaped a controlling marriage to remake herself in Hollywood, and had spent her studio years conducting small mechanical experiments in her home workshop, sat next to a composer who had spent fifteen years solving the problem of synchronizing player pianos and said: here is a military problem that no one has solved. The composer listened and said: I know how to synchronize two mechanisms at a distance without direct communication. They worked out the details together, filed a patent, and offered it to the government.
The government said no. The war ended. The composer died in 1959, the year the patent expired. The actress lived another forty years, in circumstances that were frequently difficult and sometimes humiliating, and watched from Florida as the technology that embodied their central idea was built by other people using other methods and became the foundation of the wireless world.