I worked for a company for 10 years so I built up a decent 401k balance. It's still sitting with the old company but I plan to roll it over into an IRA.

What are my options to get some Crypto/Bitcoin exposure? Based on my research, it sounds like its limited. There are some companies that pop up on Google but they are all too new and risky for a retirement balance.

Is GBTC my best option? I understand it trades at a significant discount but I'm ok with that if its my only option at this point. I would like to have some small % exposure if possible.

I'd look into Unchained Capital if I were you. You'll own actual Bitcoin in contrast to GBTC. They'll help you set up a hardware wallet with multi-sig.