Originally from ε°γ (toutoi), meaning precious, valuable or priceless, it became Japanese internet slang "γ¦γγ¦γ (or γ¦γγ¦γ)" roughly meaning someone else's actions are wholesome, or precious.
Popularised in the west by subtitled V-Tuber clips, where it was used typically during moments where the V-Tubers were acting affectionate to one another; this hard to translate word was often simply romanised. This resulted in several spellings, the most popular of which seems to be "TeeTee", whith other variant such as: tee-tee, tee tee, tei-tei, TT and te-te.
Similar to nouveau riche, nouveau teche are non-tech companies that have very recently called themselves "a Tech Company".
They often talk loudly about buzzwords of the day like blockchain, AI, ML, Big Data, IoT. More prolific ones use chained combos to impress, like "we use Big Data IoT with Blockchained AI to drive our candle making business."