Best Android app for identifying band in use?

(Sorry for the vague title.)
I have a new T-Mobile network line, an Android phone capable of band 66 & 71, and an imminent trip through an area that has historically had very spotty coverage from T-Mobile. So, it might be a good time for me to look and see if the situation has changed there, and/or band 71 has helped.

I don't need anything fancy, and would prefer free. I know I've seen recommendations for Signal Check Lite, but seems like I remember there were some caveats.
Easy access to the info would be a plus, since I'll be driving solo without many chances to stop and poke buttons.

I use network cell info lite which will tell you the band using, signal strength and other info. But it won't tell the other available bands

Thanks! That sounds like the right mix for my trip through the boonies. If I get 'any' band through most of it, it'll be fun to see if band 71 is the reason. (I know that tower density will be low.)

I installed Network Cell Info Lite, and gave it a quick test-- I think it's going to be perfect for what I want to do. A nice big signal strength indicator, with the band identified. I think it'll be possible for me to leave it running during parts of the drive, and glance at it once in a while.
Thanks for the suggestion, tom67!

An update on my exploratory trip...
My travel path took from Kansas City (northeast corner of Kansas), almost straight south through eastern Kansas to just shy of the Oklahoma border, and then west to Wichita in south kind-of-central Kansas, 150-200 miles per leg.. The route was on secondary highways-- no interstates around. To give an idea of population density, many of the towns are big enough for a Dollar General store, and way too small for McDonalds.

tom67's suggestion of Network Cell Info Lite worked great for my application! I could leave the app display on, and snooze the screen between peeks to limit screen battery drain. A couple of swipes let me see what coverage was like, and the connected band (if any....).

T-mobile's coverage in the area was... well, interesting, but far from great. The last time I'd tested, this was a large black hole for T-Mobile, and for Sprint.
My test phone was a factory-unlocked Moto E6 with a Tello GSM SIM. I did have tower connections on a large percentage of the route, but signal strength so low that I either couldn't place a call, or couldn't sustain a 2-minute call. Complete loss of tower connection was frequent, and dropping to GPRS/Edge/2G wasn't unusual.

I mostly saw Band 2.
Band 66 is one small area-- not sure why that appeared, since I thought band 66 was primarily used to relieve data congestion in busy areas.

Band 71 popped up once or twice, but with no improvements in call capability over the Band 2 I usually saw. (I know Band 71 travels further, but I must have been on the edge of whatever 'further' is....).

I was intrigued that near one of the larger towns (10,000 population), I saw Band 41 now identified as T-Mobile. It was usable if not strong, maybe 20 miles outside Wichita. I'd guess that repurposing that band let T-Mobile expand their Wichita coverage footprint. (Wichita itself has fine T-Mobile and legacy-Sprint coverage.)

Watching the bands and signal strength was interesting. I find it curious that T-Mobile 'technically' has coverage in a lot of areas that it didn't have at all the last time I tried, but that almost none of the technical coverage was actually usable coverage. It's still a black hole, other than allowing T-Mobile to color some areas of the map magenta..

My primary line is a T-Mobile postpaid plan and we drive all over the USA on a frequent basis, including in many rural areas.

I'm rarely without service and rarely have to fire up one of my other phones.

After reading your account I'm assuming that my experience must be due to roaming agreements that T-Mobile postpaid plans probably include that your Tello plan does not.

I had always assumed that I was on the T-Mobile network but there must have been times that I was roaming and didn't realize it.

I think you're probably right about the difference between T-Mo postpaid partner coverage, and native T-Mo coverage that's available on MVNOs.

I know that part of my jaunt was through an area that has long had best coverage by US Cellular-- it's kind of hard to find out what partner/roaming agreements are available to carriers, but I've read lately that T-Mobile postpaid, and possibly T-Mobile Prepaid, has roaming agreements with US Cellular.

I was pretty far off the beaten path for 'passing thru' Kansas, unless you're going there as an end point, or taking the very scenic route.. Southeastern Kansas is a long ways from Interstate Highways.

My experience w/t-mo postpaid in rural areas along roads in the E states, N. mid-West & PNW was that it was mostly roaming on at&t towers (phone actually says at&t sometimes). Some of that is not recent though. Most recent experience back through previous traveled areas has seen little change to that, some new coverage area and amazingly, some new 0 signal areas (MA & VA). I spend way more time on waterways and costal areas than on roadways. In some cases major roadways run nearby, even in sparsely populated areas so can benefit from coverage aimed at them but when in isolated waters or off the E. coast I've come to find that most often VZW is the only one "there", maybe 15% of the time at&t is the sole MNO I see.