prince Gleb Sviatoslavich of Tmutarakan - DNA confirm

Hi is my 11th remoced.grandad

He is my first cousin 28 times removed.
Means we are related to the crown princes of Kiyv.

How can I check who he is to me?
My True ancestry states:

Gleb Svyatoslavich Prince of Novgorod Rurik Dynasty

mtDNA Haplogroup: H5a2a
Y-DNA Haplogroup: I2a1a2b1a1a2 (Y4460)

Deep Dive Match! 79% closer than others who share this deep dive sample
Genetic Distance: 11.112

I got told my True Ancestry only records Maternal DNA. Is this true? And in this case, my Mothers family tree only goes up to 1860's...

Gleb maternal haplogroup is H5a2a and I am H2a1. Does this mean we connect from his mothers side and my mothers side? and potentially his great great grandmother is also my direct great grandmother?

FTDNA considered DNA material as NOT reliable for sure, and changed on the tree to Chernigov 542. So we can ASSUME that it was MAYBE Gleb, maybe not. Anyway genetically we al know that was I2a man. And so far his terminal SNP is I-S20602 by FTDNA nomenclature
https://discover.familytreedna.com/y-dna/I-FGC63213/ancient
and I-Y91535 by YFULL nomenclature
https://www.yfull.com/live/tree/I-Y91535/
MyTrueAncestry designates him as I2a1a2b1a1a2 aka Y4460.

Full path is I-S20602 \ I-Y4460 \ I-Y91535

He is My 26th great uncle.