Hi Daniel,
The phone has to be functional to access any data on it; it doesn't use an SSD as such, but rather a memory chip soldered onto the motherboard. Many, if not most, modern phones have taken to encrypting the data such that you cannot just remove the chip and read it with a different device; in those cases only the original processor can read the chip.
There are data retrieval services that may be able to get the data off your phone for you, but it's going to cost you, probably as much as the phone was worth brand new.
So your best bet would be to see if you can get the phone working again. Since you didn't investigate the issue when it originally died, it's hard to say what caused it, but if it was mine I'd invest in a new battery to start with. If the battery failed you'll see symptoms like you describe and it wouldn't be terribly expensive to pop a new one in. Even if the charging circuitry failed and couldn't charge the battery, a replacement will come with a certain amount of charge; certainly enough to power up the phone.
Have you tried plugging it in again? It's possible you ran into a glitch similar to the one I encountered on my niece's Pixel 4 XL; you can read about in on my original answer discussing what happened and how I fixed it.
Diagnose Pixel 4 XL not booting - Google Pixel 4 XL - iFixit
I'd say pop a new battery in and see what happens, then come on back and let us know and we'll see what your next step should be.
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