文頭のwhereが文法的に何なのかわかりません。 の意味は？

Where private companies are really top partners is だから
is の前は　主語だから　名詞（節）しか考えられない。
関係副詞　で　名詞節　を作っている
民間企業が・・の場所　は　　（いつも）彼らは・・持ち込む

文章が少しおかしい・文法的におかしいようには　思いますが　
意味は伝わるでしょ　　という文のような気がします
実用上、日本語でも　途中から変になってる文章というのはときどきありますし


the place where.... は　place を修飾するから　このときは　where 以下は形容詞節　

というのか　文法詳しくないですが

I'd happen to encounter the word 'where' in the TED talk just today. what do you think this ''where' is. noun? (pronoun?)
timing = 14:13 :things about yourself that you cannot change. where you come from, what you look like or who you love.
:why You Feel Anxious Socializing (and What to Do about It) | Fallon Goodman | TED.
https://youtu.be/RqAOrr_FPxo?t=854

This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
I can't find any suitable explanation about this and not likely to find it hereafter. I'd think this word 'where' is noun as for now. I don't intentionally search this, but I'll continue to stay this word 'where' in my mind till we find a solution.
If you get some solution I'm looking forward to your posting it to this section.

google 翻訳で、’where private companies are really top partner is whenever they bring their cutting edge.’といれると、’民間企業が真のトップ パートナーとなるのは、最先端の技術を提供するときです。’となり、訳はそうだろうな、と思うのですが、依然whereは、文法上どうなのかわかりません。
調べてみます。

This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
in the webliio dictionary the definition of the word 'where' are some. I wondered which definition is suitable for the question sentence. so I relied on the 'process of elimination'. at the first time relative adverb and pronoun left.
next I eliminated 'pronoun' because of none of preposition in the question snence. I'm confused with which definition is suitable 'B-1' or 'B-3'. but whichever I'd select, adverb clause would become the subject in the sentence. can it be possible? the subject (place) of the sentence can be eliminated?
if I dare to choose one I would like to choose noun for subject.
I can't grasp it like as you also.I'd continue to search the adequate one. If you get some solution, I'm looking forward to your posting it to this section.