Traveling from the 5th to Giverny around May 6,2022

No idea about tours, but it is relatively easy to do independently by train from Paris Saint Lazare to Vernon, followed by shuttle bus.

Just be aware that with May 1st being a national holiday, public transportation will be on a holiday (reduced) schedule

I was wondering the same thing. It looks like the train is 52 minutes, but the bus only runs hourly. I can see it taking a long time to actually get there.
I looked up a tour, but it had bad reviews.

There's a few companies that go: Paris-trip and Paris City vision. Chances are you won't be impressed with the tour aspect as they'll let you out of the car and voila---be back in 1 hr with little time to yourself

The shuttle buses at the Vernon Train Station are timed to meet the trains from Paris. You pay the bus driver.

Is there a way you can change your itinerary so you can go another day due to the holiday? Other than that, as mentioned this is a very easy trip via public transport.

The two times I’ve been to Giverny the bus that takes you there from Vernon was timed with the arrival of the train. When I got off the bus in Giverny I took a picture of the bus schedule so I would know which one to take for my return to Vernon to take the train back to Paris.

Edit: It looks like Pam and I were typing at the same time.

Just to note, the last time I went, the bus/shuttle was running late, so I took a taxi back to the train station so as not to miss the train.

Do double-check all transportation details. I landed in Nice on May 1, 2017, only to discover there was zero public transportation running. My taxi driver said he had made some calls to other drivers to try to assure folks coming in by plane had at least that option for getting away from the airport. Indeed, I don't remember seeing many taxis at the airport at all; another traveler and I doubled up because of the dearth of cabs.

Plenty of official information here:

https://giverny.org/gardens/fcm/visitgb.htm

That includes instructions on getting to the gardens. Note the covid regulations which may or may not change between now and the start of May -- keep watch.

Thank you to all we are actually arriving the 5th of May, realize my word choice first of may was misleading

We’ve been to Giverny twice. Both times we rented bikes as per info in RickSteves book and rode from the train station to Giverny. It’s only about 4 miles and the bike path is paved and in excellent condition. Ask for a bike lock when renting. There are bike racks at the site to leave your bike.
I would highly recommend this mode of transportation!