In the MCU we don't know. In the comics it's actually in the Null-Time Zone.

We can only speculate at the time. There is things to consider though. For example the two time travel technologies (the one the TVA uses and the one they used in Endgame) seems pretty far from each other. One you can see people shriking to 'nothingness' and the other just creates a door to where/when you want to go. We could argue that Kang is from the year 3000 something and is way more advanced than the Avengers but I would find it weird.

It could also be a place outside of time itself, like where is Kang at the end of Loki where we can see the timeline in the window. Mobius said that times passes differently but that doesn't mean that time passes at all, nobody seem to have aged at all (as seen with Renslayer who looks exaclty the same between the time she is a minutemen and the time she became judge).

We will learn more about all that in the upcoming movies and Loki season 2.

In the MCU we don't know. In the comics it's actually in the Null-Time Zone.

We can only speculate at the time. There is things to consider though. For example the two time travel technologies (the one the TVA uses and the one they used in Endgame) seems pretty far from each other. One you can see people shriking to 'nothingness' and the other just creates a door to where/when you want to go. We could argue that Kang is from the year 3000 something and is way more advanced than the Avengers but I would find it weird.

It could also be a place outside of time itself, like where is Kang at the end of Loki where we can see the timeline in the window. Mobius said that times passes differently but that doesn't mean that time passes at all, nobody seem to have aged at all (as seen with Renslayer who looks exactly the same between the time she is a minuteman and the time she became judge).

We will likely learn more about all that in the upcoming movies and Loki season 2.