if emulators are included in "for PC" then you could try The Little Mermaid. if you want purebreeds, there's You Have To Burn The Rope (even if you don't want to speedrun it, you gotta play it at least once for the awesome music).
I chose Gunpoint as my first speedgame and it's held up very well. It's a 2D puzzle-platformer where you play a spy, and though death can occur there is a quick respawn feature which makes mistakes much less tedious. Good times for Any% are under ten minutes.
some suggestions off ones I have run https://www.speedrun.com/mvm https://www.speedrun.com/there_is_no_game https://www.speedrun.com/The_Legend_of_Zelda_The_Lampshade_of_No_Real_Significance https://www.speedrun.com/hsay https://www.speedrun.com/Factory_Balls https://www.speedrun.com/yhtbtr
and if you're looking at emulation too let me know and I can suggest a whole bunch more
Dusk is a fun Quake-like clone that takes under 10 minutes to complete each episode it currently has individually, very fun to speed run for any twitch shooter gamer that has an affinity for moving very fast.
Upgrade Complete is a fun little web game I've played for years. I'd recommend checking it out and playing through it at least once, it's fairly short.
https://www.speedrun.com/Im_Still_Here If you are look for webgames, I have a ton of suggestions!
https://www.speedrun.com/seconds2square 4Head
EDIT: oh and https://www.speedrun.com/rhz ;)
https://www.speedrun.com/user/Cuttyflame Kappa
Favorite run being dice gorge 100% (5-8 min), lint (3 min), time up (3-4 min) and sawblade panic (2 min)