There's probably better options now, but I got a "Rigol ds1054" ( 4 channels and soft-unlockable to 100MHz.) back in 2016 for an electronics project and it's come in quite handy for diagnosing issues in many projects since (https://www.mups.co.uk/post/2017/11/a-sound-improvement/). Not yet needed it for our pinball machine though, but I can see times having it would save diagnostic time.

If you do decide to get a scope, I'd look over the eevblog channel on youtube and their forums. Some quite knowledgable people on there with a good set of recommendations for best bang for your buck based on requirements.