Suoma was more commonly used in the early 20th century leading up to World War II. Suoma also means "granted" in Finnish (specifically "granted by...", from Finnish "suoda" (to grant/give) and I believe it is mostly used in that sense.
The name has been given to less than 10 boys since 1900 according to Finnish population data. This could possibly be data errors. Compare that with the 5319 girls that have been named Suoma in Finland. It's not enough to change the gender to unisex, in my opinion.
It's said that the first person to use this name was Antero Warelius, a Finnish priest and writer, who named his daughter Suoma in 1849 because he thought the child was a gift given by God. In Finnish "suoda" means "to give".
Suoma also means "granted" in Finnish (specifically "granted by...", from Finnish "suoda" (to grant/give) and I believe it is mostly used in that sense.