Just bought two from here: https://www.amazon.com/gp/product/B073H552FJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Easily over 1.5TB, since I also do video.
If you're saying that Seagate external HDD is several years old I'm assuming it requires a power supply? Is that why you're not able to take it anywhere?
External SSDs are much more portable these days and can be used anywhere. I use a 1TB Samsung T5 which is a popular choice. No power supply required and they're easy to toss in a bag. I've encountered no issues. You'll be spending just shy of $200 but it's well worth it (most portable SSDs at that storage capacity are similarly priced, anyway).