Should I add an external SSD to my imac 2019 27" 5K?

I have a 2019 27" 5K imac

3.7 GHz 6-Core Intel Core i5 (i5-9600K) CPU: 6-core

40 GB RAM

I ran EtreCheck (free version), no major problems found (see report clip below),

Is it worthwhile to upgrade to an external SSD? I'm thinking of getting a 2 TB SSD Crucial X8 ($170 CDN newegg.ca) and using it both as a bootup drive/run program/extra storage, and keep my 2TB internal fusion drive as a backup drive only. The $170 is really not a big issue as I can write it off as a business expense.

I don't use any icloud backup. I use a few USB external 5-7 TB HDs as my Time Machine backups (I put them in my safe when I travel, and keep one at the office as my offsite backup).

I'd rather not have to crack open the imac to upgrade anything internally.

Would using the external SSD as both a bootup drive and to run programs/extra storage slow down the transfer speeds? Will I notice much of a performance boost with an external SSD in my system?

I generally do very light photo editing (Luminar 4/AI or GIMP), use Handbrake occasionally to convert a video, and rarely do video edits. The slowest programs seems to be Libreoffice and Mail (as I use gmail accounts).

Thx