For my tvheadend setup I was searching replacement for my dual multi-standard DVB TBS 5281 adapter, which is not working in recent kernels (>4.17) due TBS obsolete drivers. It is sad, because I was very satisfied with that hardware.
On linuxTV I have found that dual DVB-T2 usb adapter supported in linux exists and it is WinTV-DualHD. Available on amazon, which can be delivered to Slovakia. Now I have two of them:
Bus 001 Device 012: ID 2040:0265 Hauppauge Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x2040 Hauppauge idProduct 0x0265 bcdDevice 1.00 iManufacturer 3 HCW iProduct 1 dualHD
I can confirm, this DVB USB adapters are working well for Czech DVB-T2: