Upgrading from a dead TS-453BT3?

I have a TS -453BT3 unit, with 4 drives (8TB seagate ironwolf drives). Configured in a RAID 5 array. I recently was out of town for a while, and getting home found the NAS to be dead. It gets stuck on boot up cycle, gets to 'hardware initialization' and then turns itself off and starts the boot up sequence again. I am fairly certain that there is a hardware failure based on that. I am currently dealing with qnap support on that issue to see if I can get it running again, but in the meantime am planning my upgrade path.

Firstly - file recovery? I have a 4 bay hard drive dock on order from amazon coming later today, to try and recover my files. As far as I am aware the drives are all still fine so I am hoping that recovery is not too difficult. Any suggestions on recovery process / software would be appreciated (have both macs and pc available for this process) Fortunately the drives were backed up recently, so there isn't much mission-critical stuff on there, but there are a few major recurring projects that were just wrapped so not moved into cold storage / backup yet, I would like to recover these so next year when re-visiting the same content I don't have to build it all from scratch again.

Secondly - drive migration? If I buy another qnap nas, will I be able to just install the drives into the new unit, and skip the file recovery process completely? I am looking at the TS-464 as the new device, but not married to that decision yet. I was actually eyeing the synology and ugreen 4 bay options as well, but am leaning towards staying with qnap. (despite the death of this unit after less than 5 years).

Thirdly - upgrading a TS-464? Is is possible to use the QM2 board from the TS-453 in order to upgrade the 464 to have a 10GBE port as well as slots for M2 SSD expansion? (I currently have no plans for the M2 drive for caching but really want the 10gbe port, as I have a mac studio with 10gbe port, and that is a critical part of my data flow for work. If that is not possible I may look at buying a different NAS with 10gbe built in.

I do after effects animation and use the NAS as the host for project files and assets so they can be worked on one computer, then easily moved to a second machine to render while I continue to animate on the main. My existing workflow was to use the TB3 networking available in the 453BT3 in order to connect two macs with thunderbolt 3 cables, which offers much better read /write speeds than a 1gbe connection.

Any advice would be greatly appreciated, I am an independent artist so I do not have a huge budget for these types of things, but am willing to spend to have the right tools for the job if necessary.