Can Intel Windows 10 be virtualized on Apple M1 host?

No, this is impossible by definition of the word "virtualization". If it were possible, it were emulation, not virtualization.

A virtualizer gives multiple guests the impression that they are the exclusive user of something which exists. So, if you have an AMD64 CPU, then you can run multiple guests and each thinks they are the only one running on that AMD64 CPU. If you have an ARM64 CPU, you can run multiple guests and each thinks they are the only one running on that ARM64 CPU.

An emulator provides something which does not exist by implementing ("emulating") it in software. So, if you don't have a GameBoy, you can use a GameBoy emulator to run GameBoy games. If you don't have a PowerPC CPU, you can use a PowerPC emulator to run PowerPC software. If you don't have an AMD64 CPU, you can use an AMD64 emulator to run AMD64 software.

Note #1: Sometimes, the lines get a little bit muddy, because most virtualizers also contain emulators for certain hardware: for example, full-system virtualizers like Parallels, VMWare, or VirtualBox typically contain emulators for network cards, graphics cards, hard disks, CD-ROMs, keyboards, pointing devices, etc. However, once you get clear about which piece of hardware you are talking about, that confusion should go away. E.g. VMWare always virtualizes the CPU, but typically emulates the network card. Those are just two different pieces of hardware, and you can virtualize one but emulate another.

Note #2: the ARM64 version of macOS actually does contain an AMD64 emulator called Rosetta 2. However, this is not a full-system emulator; it is only intended to allow AMD64 macOS and Darwin programs to run. It does not emulate the needed parts of the system to, e.g. boot an OS, it does not emulate a BIOS or UEFI, and so on.

So, what you need is an emulator, not a virtualizer.

And indeed, there are people who have had success with emulators even as early as Fall 2020, but it cannot be done with virtualizers.

One of the most popular emulators is QEmu, which does not only support emulating AMD64, but actually many, many CPUs.

It seems that there is currently only the option to use an ARM based OS for Guest VMs. I tested it in Parallels Desktop mainly.

You can run x86 Apps emulated within the Windows 10 ARM-based Version as stated in the official FAQ from Microsoft.

So to answer your question specifically, if you don't want to use an ARM-based image it isn't possible (yet).