Is there any way to create effects like these using flutter (a CustomPaint with a special shadder or something like this)?
You can use BoxShadow widget.. You can set color, blurRadius, SpreadRadius and offset to achieve what you want..
Note in example I have used it to get a drop shadow.. But you can get a glow if you set the properties correctly..
Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(50),
boxShadow: [
BoxShadow(
color: Color(0xFF000000).withAlpha(60),
blurRadius: 6.0,
spreadRadius: 0.0,
offset: Offset(
0.0,
3.0,
),
),
]),