Replacing iMac late 2015 fusion drive with an external SSD

Hi guys,

I've owned my late 2015 27" iMac since new and unfortunately the fusion drive has finally bit the bullet after almost 10 years. I've had quite a bit of grief with it over the last few years and have had to erase, reinstall OS and restore from TM backups on several occasions. A couple of days ago it was unresponsive so went through the process again but I think it's finally dead as I can't get it back up and running successfully.

I've read that a workaround is to use an external SSD as the main boot drive/hard drive. This seems fairly straight forward and is obviously more cost effective than shelling out for a new machine. Aside from the fusion drive issue the rest of the iMac is in really good condition, the screen is excellent and I upgraded the RAM for design work several years ago. It would be a shame to end up with a useless paper weight.

My prior iMac to this was a 2009 27" which had the hard drive bite the bullet after 6 years. I attempted a hard drive swap myself with some level of success but those machines were easier to open up and I wouldn't want to attempt the same with my current machine. Plus the cost of having a professional do it may be too high.

Can anyone recommend a suitable 2TB external SSD and is it simply a case on installing the OS on the external drive and telling my iMac to completely ignore the internal fusion drive? I would be planning on migrating all my data from the TM backups to the new external SSD and having that as my main drive. I have multiple external hard drives with TM backups on so my data is safe.

Thanks in advance.

[Re-Titled by Moderator]