Some extra options you might want to consider:

• Having the device act like a DLNA renderer. You still need it to run a graphical stack and a DLNA app, but you can control it with a DLNA controller app on your phone, and tell it to fetch content from your Jellyfin server if you activate the DLNA plugin so it will act like a DLNA server. DLNA needs network broadcast so it will work if the stick/phone/server all all on local LAN but typically can’t cross VLANs.
• Having the device run a Tailscale client alongside Kodi or connecting to Jellyfin with a browser or client. If you also put Tailscale on the server you will be able to securely connect to it even on vacations (hotel TV for example).