5m is essentially the fundamental length of active pixel led (that can be fully animated) in either it's string or tape form. There are some things available longer but they are rare.
I had 8 strings up (400 pixels) on the tree on the drive for Christmas (our Close has a bit of a friendly competition) running 3D animations, very cool.
I'd be happy to provide guidance but the boards I use are effectively someone else's side hustle. The amount of software install or soldering is minimal, if you can do leisure electrics or use a code reader it's no more. He does now do complete ready to go boards though:
www.mottramlabs.com
It uses then Open Source WLED project
kno.wled.ge
By default the boards fire up as a WiFi access point, connect with your phone and it will prompt to "sign in" like public WiFi but take you to the internal app where you can configure and create (1000s of light show possible from the effects and pallettes).
If you have a WiFi access point you can connect them to that in which case they can sync (have 4 flag poles all doing the same thing) or even operate as a single virtual pattern.
This isn't the best time of year to get hold of the string type LEDs, supply chains are exhausted after Christmas. I usually get BTF Lighting branded ones - quality can still be a bit exciting but they seem more reliable than most
With addressable LED the key limiting factor is voltage drop (told you it's like leisure electrics!) so with a string of 50 5V pixels you'd need about 2A to fully drive them and have them all white, but as most patterns won't do that you can usually use about 1A so USB power pack range. WLED is smart enough to dynamically tune the brightness if you configure it to anyway. You can connect strings or tapes together, you can run 100s to 1000s of pixels from the controller, but for longer runs you do need to inject power at every other junction to stop voltage drop issues.
In terms of costs a Mottramlabs control board tends to be £10 region, £15 with a decent waterproof junction box. 50 pixel strings tend to be £20 region.