I used to speedrun Super Metroid on an emulator on my PC, so recording wasn't an issue. But I'm new to speedrunning on my switch for Metroid Dread. Could someone explain (or send me a link) how to record my speedruns onto my PC?

I guess there always the "film your TV screen" way but the simplest one is to get yourself a capture card like the Elgato HD60S (this is what I use for my Switch) and record through OBS.

You'll have to purchase a capture card, like Lefloic has suggested. I also have the Elgato HD60S. If you're unfamiliar with capture cards, they get installed in your computer, and you basically run two HDMI cables between your display, the switch, and the computer. Then you can use software on your computer to record the capture card's display of your game. The card costs ~$150 I believe. If this is something you'd need help doing once you purchase the card, I'd be happy to help.

Here’s a discussion on capture cards if you end up deciding to go that route.

https://www.speedrun.com/streaming_recording_equipment/thread/1mkl1

A capture card is the only way to record the Switch itself. I'm personally using a cheap one called "Mirabox" got it for under $100 CAD. It records well from my experience. Solid 60 FPS from it at 1080p.

I have used a external capture card that works pretty well to be honest, i found it on amazon and was going to change it for an internal one but since its working pretty well i havent changed it

https://www.amazon.com/gp/product/B08QF6DHZD/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&th=1

I use a this ZettaGuard 4K 1x2 HDMI Splitter 1... https://www.amazon.com/dp/B01M8PFCZV?ref=ppx_pop_mob_ap_share to send to a tv and my pc. Then used a hdmi2usb device, dont remember exactly what it was, till i got this https://www.amazon.com/dp/B093V5WF8Y/ref=cm_sw_r_apan_glt_fabc_50S7ZNZEN3QWRA5YR94N . Both worked great but i didnt like the length of the hdmi2usb.