I put some chinesium coil packs on my 05 prius. They were marketed as generic and I got what I deserved. They worked well for 5000 miles then one crapped out magestically. The car hated its sudden-onset misfire so much it switched to electric-only and shut down after that was depleted.
Ripped them all out and got some used Densos that I think were genuine.
If you get a knockoff exotic metal plug you'll likely get something that runs, but, jeez, the little tips can come off and smash your valves. Go with rockauto or an online franchised dealer.
For a lawnmower, maybe a little different. The parts pipeline is so contorted on those anyway there's a good chance of having good stuff mixed in, or at least the same stuff with different labels.