Since you have Unifi APs, having a separate vlan for guests isn’t a requirement, as long as you can live with the guest wifi only having access to the internet, and not to anything local, including other devices using the same SSID.
Doing it with vlans is more flexible, but as @kevdog said, vlans (or multiple lans in general) add complexity, especially if you want to allow access to devices on another broadcast domain (lan/vlan). And there isn’t a single solution that will work with different types of devices, i.e. getting chromecast to work doesn’t mean sonos would work, or AppleTV.
So if you decide to use vlans, be prepared to spend a lot of time finding something that works, by searching, reading and trial and error testing.
But now may be a time that you have more time to work on things around the house, and having something to keep you occupied can be a good thing if you can’t leave the house.
For a good review of networking topics, including the best vlan explaination I am aware of, I recommend Ed Harmoush’s Practical Networking web site. Here’s the CCNA-index, but don’t be put off, everything on the list (with the exception of EIGRP, and some of the Cisco specific configurations) will apply to most vendors. I recommend following in order, the topics are short and well explained.
One thing Ed doesn’t cover as well as I wish he did is routing tables, and how the router uses them. He covers the network/host and mask in subnetting, but doesn’t cover how the router or host uses its routing table. It is probably so basic for him that he doesn’t cover it other than in passing (or if he does, I didn’t see where).