I'm curious - what are the notices about?

I like the idea, but I'd be worried about:

1 - It getting nicked (we rent a room in a larger building)

2 - somebody else breaking it when I'm not there

3 - fiddling with the electronics, mounting on the wall etc

4 - it getting hacked and just showing porn 24/7 or something like that

However, I will often have my laptop there, normally to get some different (and louder! Can never get much volume from my phone, even with speakers) music, also as a sort of register for the mini Artemis BJJ Camps I run.

After we can open up in the UK again, I'll probably use that laptop to keep the Zoom BJJ solo drill classes going. I am certain that even when we are allowed to train, there will be some who are understandably still reticent to step back on the mats. So, I can use one of the daytime classes to keep providing content they can use at home.

Did you try post-it? On the screen?

I see you're a bleeding edge of technology kinda guy. ;)

I was thinking of having a slideshow of training pictures along with upcoming important dates / notices

We've got our own premises so no worries about it getting nicked

I was thinking of using something like a raspberry pi to run the screen with remote login to update images / notices / etc...

Sounds like a fun idea. I've got a random mini projector thingy that works off a memory card,. So, I was thinking of projecting old Mundials up on the ceiling during GrappleThons, something like that. :)

I've done this in my old gym, just used an old PC; easy :)

we actually have TWO Tv's in our gym and use neither lol.. We display some of the fights or youtube some stuff every once in a while on the big tv. the smaller one is for the kids in the sitting area and they dont use it either. ( they always got tablets or phones.. My Gym is a huge open area with a 8x 30ft sitting area that is only used when the parents are there for the kids class and empty during the adults.

but if your looking into doing digital signage.. Go with a Raspberry pi pc , even a $5 pi zero and save you some time and money..

That was my thought, but I'm not sure of the software to use to run the signage

We have two that use Amazon Fire sticks, one in the lobby that plays a YouTube playlist of members' competition matches and general jiu-jitsu interviews/highlights, and the other in the pre-mat/shoe dropoff/water-fountain area that cycles a bunch of photos from promotions, podiums, etc.

this si what i would setup for anyone that needs it done... Its simple and WELL worth it.
its a 3 parter... BUT Follow it exactly how to do it. ( you will want to do ALL KINDS of other stuff)
https://youtu.be/dC3joWHr8Ks
https://youtu.be/0_sBYOI3trc
https://youtu.be/qnKCj6iObDA

I've used screenly and an r-pi to set up a digital sign at work, and it's much more flexible for "digital sign" use cases than the fire-stick, but the fire stick is much easier to set up if you're just doing simple "play this list of media" type stuff.