Technically I think all fan made space marine chapters are canon in 40k. Not sure if this specific way he made it would ever hold up normally if judged outside this story.
Founding of Legions of Blacksouls (Fan Made Chapter)
Video Games · ElJonson
See this! I just gifted the story: Pizza
ch 171 Grand Strategy!
Games · Antihero
See this! I just gifted the story: Ice cola
ch 143 Heroic Task
Games · Antihero
Congratulations on year of wonderful writing and great storytelling.
ch 501 Swimming Pool
Book&Literature · EsliEsma
Congrats
ch 900 Christmas Day Divulges Ⅴ
A Bend in Time
Book&Literature · EsliEsma