I've been using Nucleo for the last couple of weeks for a few different projects, and I must say it's quite impressive. The icon libary is pretty extensive for being a relatively new app and Sebastiano and team are adding more and more icons pretty regularly. You can check out the Nucleo Dribbble page to get a feel for what's available.
You can search for specific icons, choose outlined or solid mode, and export them as .pngs or .svg. Super simple.
You can pay a flat fee of $49 for a year or $99 for unlimited access. I regularly design my own icons, but there are lots of times I just need quick access to some and Nucleo is becoming a go to for me.