Here's what I recommend: basically, u really want an intervalometer rather than just a basic switch for star trails. In my experience, the Vello ShutterBoss II Remote Switch with Digital Timer for Canon with 3-Pin Connection is the best bet for a 7D. I've been using it lately and it's actually super helpful because it handles 1-second to 99-hour exposures... though I guess nobody actually shoots for 99 hours lol. Honestly, I'd skip the Canon RS-80N3 Remote Switch cuz even though it's official, it doesn't have a screen or timer functions built-in. Just be careful with the N3 pins tho!! They're kinda fragile and if u force it, u might break the port. I mean, the Vello feels pretty secure once it's locked in. Plus, it uses AAA batteries which are easy to find. So yeah, it's a solid budget pick. gl!

TL;DR: A wireless intervalometer like the Pixel TW-283 N3 Wireless Remote Shutter Release is a lifesaver for long exposures cuz it removes all physical contact with the camera. I went through this last year when I started doing deep sky stuff on my 7D. Honestly, even with a sturdy tripod, just touching the wired remote to lock the shutter in Bulb mode was giving me tiny bits of vibration. I ended up grabbing the Pixel TW-283 N3 Wireless Remote Shutter Release and I've been really satisfied with it. It uses the 2.4GHz frequency so the range is great, and it hasn't flaked out on me once during 4-hour star trail sessions. What I love is that it's basically a 2-in-1; you can use it wirelessly or just plug the remote directly into the N3 port if you wanna save battery. It's way more budget-friendly than the Canon RS-80N3 Remote Switch but gives you way more technical control for intervals. 👍

This ^

Quick question - before I give full advice, are you gonna be shooting in super cold temps or really high humidity? I ask cuz some budget LCD screens basically freeze up or get moisture inside, which is a total nightmare when you're like 4 hours into a star trail and the display goes blank. Honestly, after 10+ years of this, I've learned that wired is usually safer than wireless for long exposures. Wireless receivers are just one more thing to run out of juice mid-shot. You want a solid physical connection to that N3 port so it doesn't wiggle loose. 1. JJC TM-A LCD Timer Remote Control for Canon EOS 7D - This is the best value imo. The N3 connector is solid and won't flake out like some of the super cheap clones.
2. Neewer LCD Timer Shutter Release Remote Control for Canon EOS 7D - If you're really watching your wallet, this works fine, but the plastic feels a bit thinner... just be careful with the cable bend!! Let me know about the weather conditions and I can narrow it down. gl!

Wait, I gotta ask a couple things before you pull the trigger: - What's your hard budget limit here? Like, are we talking under $25 or can you go higher for something more solid?
- Are you planning to do any cold weather shooting, or is it mostly just clear summer nights? Your definitely right about wireless being better for vibrations, but the market is kinda flooded with identical-looking gear these days. Basically, most of the third-party stuff you see on Amazon or eBay comes from the same few factories, just with different logos slapped on 'em. Tbh, it makes it hard to know if youre actually paying for quality or just a brand name. 1. The cheaper brands usually have thinner cables that might crack over time if you go the wired route.
2. The "mid-tier" third-party brands usually have better weather sealing around the battery door, which is huge if you get heavy dew overnight. Honestly, its all about finding that middle ground where it doesn't feel like a toy but won't break the bank if you accidentally drop it in the dark!!!

Wait really?? Thats actually super helpful. I always thought it was the other way around.