Share your experience!
can you recommend most suitable usbhdd to purchase and where to purchase
Sony seem to recommend a regular HDD (not a USB stick and not an SSD) that is at least 64 GB in size "larger than 32 GB", other than that, there doesn't seem to be a specific brand that's recommended: https://www.sony.co.uk/electronics/support/articles/00148248
sorry new to this what is a regular hdd
A regular HDD is any Hard Disk Drive you can get off the shelf at a computer store, nothing specific or special about it is required for that feature according to Sony, as long as it's larger than 64 GB that is.
By connecting it to the USB 2 port, you can find it has HDD REC noted on it as illustrated in the official Start-up Guide.
thanks