Your pika fundamentals seem alright, and you have periods of pretty decent pika play. Where I think you can do the most improvement is your edgeguarding (as robin mentioned), matchup experience, and your approach philosophy i guess. I could be misinterpreting it, but it felt like often when you were on offense you'd make a plan, put in the inputs of said plan, and not really react to what the opponent did. So if you got your hit in with a nair or whatever, the rest of the combo would go fairly well (as long as they didn't DI too awkwardly), but if you traded or missed instead, you would miss an lcancel on your next move (as you didn't expect to not jump, etc.) or miss the tech when you hit the ground, and then get up, shield, and watch your opponent for an opening to uair/grab or get away. You'd kind of lock up as you thought up a new plan. That will probably come more naturally as you get more matchup experience, but I think figuring out how to be more adaptable in your approaches abandon/change plans asap when they don't work out will help your play as pikachu a lot.
Your edgeguarding needs work. It would be a bit easier to critique if you went for edgeguards more often, but it seemed like most of the time you would just fsmash and hope the opponent missed their sweetspot or timed their fastfall after upB poorly. You went off the edge a few times, which is good to see, and it worked out a couple times. It mostly felt like almost always you just expected them to recover in a particular way, and would try to hit them with fsmash. Pika has a ton of good tools against spaceys, he's super dangerous against them off the edge, but even if you aren't comfortable off the edge a down-angled ftilt works much better than fsmash in almost all situations. It hits below the edge, is impossible to avoid via sweetspot from most angles, comes out faster so that you can use it reactively, and it has active frames longer than fsmash so is more lenient in that regard. The main issue in my mind, though, was that you wouldn't react much to what the opponent did to recover. If they look like they're trying to recover high, chase them or intercept them as they fall. If they look like they're setting up for an overB to the stage, ftilt early. If they recover low, intercept with a run off aerial, ftilt, or just ledgehog if it doesn't look like they can make it to the stage. Mostly, be ready to react to multiple recovery options, and then react. If you really feel like you have a read on them, then go for it, but a lot of the time you'll have to react.
Edit: Oh yeah, and iRobinhood, I don't know exact percents of when fox/falco/falcon die on those stages, i just have ballpark numbers. They all die around 110ish (before usmash) on FD, and 100ish on stadium iirc.