Habranthus × floryi Traub, Pl. Life 7: 121 1951. ;
.
Lilies for ID : Nairobi, Kenya : 05APR21 : AK-04: 3 images.
These are very old pictures taken in Jan, 2009.
Habranthus brachyandrus can also be a possible id.
Maybe Habranthus × floryi as per comparative images at Pacific Bulb society.
But these were growing wild by the roadside, not cultivated.
Is there any native species in Kenya ?
I am not aware.
None of the species mentioned by you is likely to be found wild as per POWO 1 and POWO 2
.
References: POWO The Plant List Ver.1.1 WCSP IPNI Pacific Bulb society