You are talking about an Android device, there may be 100.000 small differences between real and emulated devices. Even eliminating all those differences that can be "fixed" requires quite some work.
Just the execution speed is an indicator you can't forge that easily. To emulate an ARM device that costs US$99, you may need a PC that costs more than US$1000, and then the execution speed of an ARM emulator will still be lower than the physical device. This is because emulating an ARM CPU on an x86 CPU is difficult and requires a lot of CPU resources.
Even if you would use one of the new Apple computers with an M1 ARM chip (or another device that runs a fast ARM-based chip which therefore understands most of the ARM commands directly), there will still be differences on the code-level you can detect and therefore guess that with a high probability it is an emulator.
Another problem is that assuming you would be able to create an emulator that an app can't detect as an emulator, you then sell it to anyone on the internet. Very soon those people you don't want an app to run on an emulator will recognize your emulator, get it and tear it apart until they have found a way to still detect it.
Therefore from my perspective, the answer to your question is: yes, with a high probability, there are emulators at the moment no app can detect as emulators. However, to keep it that way, those emulators are never published and cannot be bought or retrieved anywhere.
For example, Anti Virus companies most likely have such an emulator because malware usually contains the most sophisticated way to detect if they are running in an emulated environment or a regular device. Running in an emulated environment for malware usually means there is someone analyzing it (which obviously the malware author doesn't want to).
