Legal regulations for eBikes

Hey everyone!

Been spending a lot of time in the garage lately, dreaming up a new custom build – thinking a mid-drive on a beefier frame for some trail riding. But it got me thinking, especially with all the different motor kits out there, how do you guys navigate the legal side of things when you're building from scratch? Are there specific wattage limits or speed cut-offs you aim for to keep it street legal, or even trail legal, depending on where you ride? It feels like a bit of a grey area sometimes when you're not buying an off-the-shelf Class 1/2/3.

Cheers, eBike_Dreamer